Name: Lemon Oatmeal Crumble Bars
Prep time: 15 min
Cook time: 35 min
Total time: 1 h 50 min
Cuisine: American
Ingredients: 1 cup all-purpose flour; 1 cup old-fashioned rolled oats; 1/2 cup light brown sugar, packed; 1/4 cup granulated sugar; 1 tsp baking powder; 1/4 tsp salt; 1/2 cup unsalted butter, melted; 2 lemons, zested and juiced (about 1/3 cup juice); 2 large eggs; 1 can (14 oz) sweetened condensed milk; 1 tsp vanilla extract

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These lemon oatmeal crumble bars are the perfect mix of bright citrus flavor and rustic, chewy texture. With a buttery oatmeal crust and crumble topping sandwiching a sweet and tangy lemon filling, they make a fantastic treat for any time of day—whether it’s an afternoon snack, picnic dessert, or casual party bite.

Why You’ll Love This Recipe

I love how easy and satisfying these bars are to make. The combination of lemon and oats delivers both a fresh zing and hearty warmth in every bite. They don’t require any fancy techniques or ingredients, yet the end result is incredibly flavorful. I also appreciate how versatile they are—I can serve them cold, at room temperature, or even slightly warm with a scoop of vanilla ice cream.

Ingredients

(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)

All-purpose flour
Old-fashioned rolled oats
Light brown sugar
Granulated sugar
Baking powder
Salt
Unsalted butter, melted
Lemons (zest and juice)
Eggs
Sweetened condensed milk
Vanilla extract

Directions

I preheat the oven to 350°F (175°C) and line an 8×8 or 9×9 inch baking pan with parchment paper.
In a large bowl, I mix together the flour, oats, brown sugar, baking powder, and salt. I pour in the melted butter and stir until crumbly.
I press about two-thirds of this mixture into the bottom of the prepared pan to form a solid crust.
In another bowl, I whisk together the sweetened condensed milk, fresh lemon juice, lemon zest, eggs, and vanilla extract until smooth.
I pour the lemon mixture over the crust, spreading it evenly. Then I sprinkle the remaining oat mixture on top for the crumble.
I bake for 30–35 minutes, or until the top is lightly golden and the lemon filling is set.
I let the bars cool completely in the pan, then refrigerate for at least 1 hour before slicing into squares.

Servings and timing

This recipe makes about 12 bars. The prep time is around 15 minutes, baking takes 35 minutes, and chilling time is at least 1 hour—so they’re ready to enjoy in under 2 hours total.

Variations

I sometimes add shredded coconut to the oat crumble for a tropical twist.
For extra tang, I mix a bit of cream cheese into the lemon filling.
If I’m craving something fruity, I’ll add a thin layer of raspberry or blueberry jam between the crust and lemon layer.

Storage/Reheating

I store the bars in an airtight container in the fridge for up to 5 days. They hold up well and taste great cold. For longer storage, I freeze them in a single layer, then transfer to a container or bag. I thaw them in the fridge or at room temperature before serving. I don’t usually reheat them, but they’re nice slightly warmed in the microwave for a few seconds if I want a softer bite.

FAQs

Can I use bottled lemon juice?

I prefer fresh lemon juice for the best flavor, especially since the zest adds so much brightness. Bottled juice can work in a pinch, but it won’t have the same vibrant taste.

What kind of oats should I use?

I use old-fashioned rolled oats for the best chewy texture. Quick oats will make the crumble too soft, and steel-cut oats don’t work for this recipe.

Can I make these bars gluten-free?

Yes, I swap the flour with a gluten-free all-purpose blend and use certified gluten-free oats. The results are just as delicious.

How do I know when the bars are done baking?

I look for a lightly golden top and set lemon filling. It should no longer jiggle in the center. A slight browning at the edges means it’s just right.

Can I double the recipe?

Absolutely—I double the ingredients and bake it in a 9×13 inch pan. I usually add 5–10 extra minutes to the baking time and keep an eye on the top for doneness.

Conclusion

Lemon oatmeal crumble bars are a go-to dessert for me when I want something refreshing, easy, and crowd-pleasing. They deliver the perfect balance of sweet and tart with a comforting, crumbly texture that’s hard to resist. Whether I’m baking for guests or just treating myself, these bars always hit the spot.