Strawberry Oatmeal Crumble Bars

Strawberry Oatmeal Crumble Bars are buttery, fruity, and absolutely irresistible! With a golden oat crust, juicy fresh strawberry filling, and a crispy crumble topping, these bars are perfect for brunch, dessert, or an afternoon snack with coffee.

Why You’ll Love This Recipe

Buttery, and layered with sweet strawberry filling and a golden oat crumble topping. The combination of fruity, jammy center and crisp crumble makes every bite perfectly balanced. Easy to make and great for sharing.

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Ingredient List

Crust & Crumble

• 2 cups old-fashioned rolled oats
• 1½ cups all-purpose flour
• 1 cup packed brown sugar
• 1 teaspoon baking powder
• ½ teaspoon ground cinnamon
• ½ teaspoon salt
• 1 cup (2 sticks) unsalted butter, melted

Strawberry Filling

• 4 cups fresh strawberries, hulled and diced
• ½–¾ cup granulated sugar (adjust based on berry sweetness)
• 1 tablespoon lemon juice
• 1–2 tablespoons cornstarch (for thickening)

Optional Toppings

• ½ cup chopped nuts (pecans or almonds)
• ½ teaspoon vanilla extract
• A pinch of nutmeg

Substitution Notes:

• Butter: Can use coconut oil for a dairy-free version (bars will be slightly less rich)
• Strawberries: Swap with blueberries, raspberries, or mixed berries
• All-purpose flour: Use a 1:1 gluten-free flour blend if needed
• Brown sugar: Light or dark brown sugar both work beautifully

Why These Ingredients Work

Old-fashioned rolled oats give these bars their signature hearty texture and help the crumble hold together without being too dense.

Brown sugar adds moisture and a deep caramel-like sweetness that complements the fruit perfectly.

Melted butter creates that rich, buttery flavor and helps bind the oat mixture into a crumbly, cookie-like texture.

Cornstarch is the secret to a filling that’s jammy but not runny — it thickens the strawberry juices as they bake.

Lemon juice brightens the strawberries and balances the sweetness, making each bite taste fresh and vibrant.

Cinnamon adds warmth and depth without overpowering the fruit.

Essential Tools and Equipment

• 9×13-inch baking pan (metal or glass)
• Parchment paper (makes cleanup and cutting SO much easier)
• Large mixing bowls (2)
• Measuring cups and spoons
• Wooden spoon or spatula for mixing
• Sharp knife for cutting bars

How To Make Strawberry Oatmeal Crumble Bars

Step 1: Preheat Oven

Preheat your oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving some overhang on the sides.

Step 2: Make Crust & Crumble Base

In a large bowl, combine the oats, flour, brown sugar, baking powder, cinnamon, and salt. Pour in the melted butter and stir with a wooden spoon or spatula until the mixture becomes crumbly and holds together when you press it between your fingers.

Step 3: Form the Bottom Layer

Take about two-thirds of the crumble mixture and press it firmly into the bottom of your prepared pan. Use your hands or the bottom of a measuring cup to really pack it down — this creates a sturdy crust that won’t fall apart when you cut the bars.

Step 4: Prepare Strawberry Filling

In another bowl, combine the diced strawberries, granulated sugar, lemon juice, and cornstarch. Stir gently until the fruit is evenly coated and the cornstarch is completely dissolved.

Step 5: Assemble Bars

Evenly spread the strawberry mixture over the pressed crust layer, spreading it all the way to the edges. Then sprinkle the reserved crumble mixture over the top of the strawberries.

Step 6: Bake

Bake for 40–45 minutes, or until the top is golden brown and you can see the strawberry filling bubbling around the edges.

Step 7: Cool Completely

This is the hardest part! Allow the bars to cool completely in the pan for about 1–2 hours. I know it’s tempting to cut into them right away, but cooling helps the filling set properly so your bars slice cleanly without falling apart.

Step 8: Cut & Serve

Once cooled, lift the entire slab out of the pan using the parchment paper overhang. Place it on a cutting board and cut into 12–16 squares or rectangles.

You Must Know

• The bars MUST cool completely before cutting, or the filling will be too loose and your bars will fall apart. Patience is key!
• Use old-fashioned rolled oats, not quick oats. Quick oats will make the texture mushy instead of pleasantly chewy.
• Taste your strawberries first — if they’re very sweet, use ½ cup sugar; if they’re tart, go for ¾ cup.

Personal Secret: I always add a pinch of nutmeg to my strawberry filling. It’s barely detectable, but it adds this warm, mysterious depth that makes people say, “What’s in these?!”

Pro Tips & Cooking Hacks

• Press the bottom crust FIRMLY — this is crucial for bars that hold together. Use the bottom of a flat measuring cup to really pack it down.
• Don’t overmix the crumble — you want it to look crumbly, not like dough. Stop mixing as soon as the butter is incorporated.
• Leave some larger crumble chunks on top — they’ll get extra crispy and golden in the oven.
• Line with parchment paper — this makes lifting the bars out effortless and cleanup a breeze.
• If the edges brown too quickly, tent the pan loosely with foil during the last 10 minutes of baking.

Flavor Variations / Suggestions

Berry Bliss

Replace strawberries with a mixed berry blend (strawberries, blueberries, raspberries, blackberries).

Peach Crumble Bars

Use diced fresh or frozen peaches instead of strawberries and add ¼ teaspoon almond extract to the filling.

Lemon Strawberry

Add 1 teaspoon lemon zest to the crumble mixture for extra citrusy brightness.

Chocolate Drizzle

Once cooled, drizzle melted white or dark chocolate over the top for an elegant finish.

Nutty Crunch

Mix ½ cup chopped pecans or sliced almonds into the crumble topping before sprinkling.

Spiced Version

Add ¼ teaspoon nutmeg and ¼ teaspoon ginger to the crumble mixture for warm, cozy flavors.

Make-Ahead Options

These bars are perfect for meal prep and actually taste even better the next day!

To Make Ahead:

• Prepare the bars completely, let them cool, and cut into squares. Store in an airtight container in the refrigerator for up to 5 days.
• You can also prepare the crumble mixture and strawberry filling separately up to 1 day ahead. Store them in the fridge, then assemble and bake when ready.

To Freeze:

• Baked and cooled bars freeze beautifully! Wrap individual bars in plastic wrap, then place them in a freezer-safe bag or container. Freeze for up to 3 months.
• Thaw overnight in the refrigerator or at room temperature for 1–2 hours.
• You can also freeze the unbaked assembled bars. Cover tightly with plastic wrap and foil, freeze for up to 2 months, and bake from frozen (add 10–15 minutes to the baking time).

Recipe Notes & Baker’s Tips

• Room temperature works best for serving these bars — the flavors are most pronounced and the texture is perfect.
• For cleaner cuts, chill the bars in the refrigerator for 30 minutes before slicing, then bring to room temperature to serve.
• The filling will look quite juicy when you first mix it — don’t worry! The cornstarch works its magic during baking.
• Use fresh strawberries when possible for the best flavor, but frozen strawberries work too (just don’t thaw them first, and add an extra 5–10 minutes to the baking time).

Serving Suggestions

These bars are incredible on their own, but here are some of my favorite ways to serve them:

• With vanilla ice cream or fresh whipped cream for an indulgent dessert
• Alongside your morning coffee or tea for a sweet breakfast treat
• Dusted with powdered sugar for a pretty presentation
• With a dollop of Greek yogurt for a lighter option
• Cut into smaller pieces and served on a dessert platter at parties

They’re perfect for summer picnics, potlucks, bake sales, Mother’s Day brunch, or anytime you want something homemade that feels special without too much fuss.

How to Store Your Strawberry Oatmeal Crumble Bars

Room Temperature: Store in an airtight container for up to 2 days. The bars will stay fresh, but I recommend refrigerating them if your kitchen is warm.

Refrigerator: Store in an airtight container for up to 5 days. Let them come to room temperature before serving for the best flavor, or enjoy them chilled!

Freezer: Wrap individual bars in plastic wrap, then store in a freezer-safe container or bag for up to 3 months. Thaw at room temperature or in the fridge overnight.

Reheating: If you prefer warm bars, microwave for 15–20 seconds or pop them in a 300°F oven for 5–7 minutes.

Allergy Information

Contains: Wheat (gluten), dairy (butter)

Allergen-Friendly Substitutions:

• Gluten-Free: Use certified gluten-free oats and a 1:1 gluten-free flour blend
• Dairy-Free: Replace butter with melted coconut oil or vegan butter
• Nut-Free: These bars are naturally nut-free unless you add optional nuts in the topping
• Vegan: Use vegan butter and ensure your sugar is vegan-friendly

Questions I Get Asked A Lot

Can I use frozen strawberries instead of fresh?

Absolutely! Just don’t thaw them first — use them straight from the freezer. You may need to add 5–10 extra minutes to the baking time, and the filling might be slightly more liquid, so I’d add an extra ½ tablespoon of cornstarch.

My filling is too runny — what did I do wrong?

This usually happens when there’s not enough cornstarch or the bars weren’t cooled completely. Make sure you use at least 1½ tablespoons of cornstarch for juicy strawberries, and always let the bars cool for the full 1–2 hours so the filling can set properly.

Can I make these in a smaller pan?

Yes! Use an 8×8-inch or 9×9-inch pan for thicker bars. You’ll need to increase the baking time by about 10–15 minutes and keep an eye on the top so it doesn’t over-brown.

The crumble topping is falling off — how do I prevent this?

Make sure you’re pressing the bottom crust layer very firmly before adding the filling. Also, don’t crumble the topping too finely — leaving some larger chunks helps it stay in place and creates better texture.

Can I use quick oats instead of old-fashioned oats?

I don’t recommend it. Quick oats will make the bars mushy and dense instead of having that lovely chewy texture. Stick with old-fashioned rolled oats for the best results!

💬 Tried this recipe? Leave a comment and rating below! I’d love to hear how your strawberry oatmeal crumble bars turned out! Did you try any fun variations?