Name: Lemon Oatmeal Crumble Bars Recipe
Prep time: 20 min
Cook time: 25 min
Total time: 45 min
Cuisine: American
Ingredients: 7 Tablespoons (99g) unsalted butter, softened to room temperature; 3/4 cup (150g) packed light or dark brown sugar; 1 teaspoon pure vanilla extract; 1 cup (125g) all-purpose flour (spooned & leveled); 1 teaspoon baking powder; 1/4 teaspoon salt; 1 cup (85g) old-fashioned whole oats or quick oats (not instant); 1 (14-ounce weight) can full-fat sweetened condensed milk; 6 Tablespoons (90ml) lemon juice (about 2 lemons); 1 Tablespoon lemon zest (about 1 lemon)

Jump to Recipe

If you adore the tangy brightness of lemon desserts and the comforting wholesomeness of an oat crumble, say hello to your new obsession: Lemon Oatmeal Crumble Bars. This treat layers sunny lemon filling between a tender, brown sugar oat crust and golden crumble topping for a dessert bar that’s chewy, zesty, and simply irresistible. Whether you’re sharing with friends over coffee, serving at a spring brunch, or sneaking a piece as a midnight snack, these bars strike the perfect balance of sweet, tart, and buttery richness in every bite.

Lemon Oatmeal Crumble Bars Recipe - Recipe Image

Ingredients You’ll Need

Lemon Oatmeal Crumble Bars come together with a handful of kitchen staples that play big roles in texture and flavor. Each ingredient counts, delivering that crumbly oat bite, luscious lemon layer, and a golden hue irresistible to dessert lovers. Here’s what you’ll need, each with a tip to make your bars the best they can be!

Unsalted butter: Seven tablespoons brings just enough richness for crust and crumble; let it soften to room temp for easy mixing.
Light or dark brown sugar: For deep, caramel notes and a chewier crumb, pack it tight in your measuring cup for accuracy.
Pure vanilla extract: This small addition lifts all the flavors and rounds out the oat base with warmth.
All-purpose flour: Spoon and level to avoid tough bars; this is the backbone holding everything together.
Baking powder: Gives the crust a gentle lift and helps keep the crumble light, not dense.
Salt: Just a bit sharpens all the flavors and prevents your bars from tasting flat.
Old-fashioned whole oats or quick oats: These oats (just not instant) add hearty chew and classic crumble texture—choose your favorite.
Full-fat sweetened condensed milk: This is what makes the lemon filling creamy, dreamy, and perfectly set—don’t swap with low-fat!
Lemon juice: Freshly squeezed is best for that zingy punch; about two lemons will do it.
Lemon zest: All the fragrant oils live in the zest—it’s what gives these bars their signature brightness.

How to Make Lemon Oatmeal Crumble Bars

Step 1: Prep Your Pan and Oven

Start by preheating your oven to 350°F (177°C). Line an 8-inch square baking pan with parchment paper, letting the edges hang over for easy removal later. This little move keeps your Lemon Oatmeal Crumble Bars from sticking and makes cleanup a breeze.

Step 2: Make the Oatmeal Crust and Crumble

Grab your stand mixer or handheld mixer and beat the softened butter and brown sugar together on medium-high speed for about one minute. The mixture should look creamy and well combined. Add in the vanilla extract and mix again briefly. Next, sprinkle in the flour, baking powder, salt, and oats, mixing just until everything looks like coarse, crumbly sand. Don’t worry if it seems dry—this is exactly what gives your Lemon Oatmeal Crumble Bars that irresistible texture!

Step 3: Form the Bottom Crust

Take a little more than half of this crumbly oat mixture and gently press it into the bottom of your prepared pan. Be firm, but don’t overdo it; you want the crust to hold together while still feeling tender. Pop the pan into the oven for 12 minutes to set the base.

Step 4: Whip Up the Lemon Filling

While the base is baking, get started on your filling: in a medium bowl, whisk together the sweetened condensed milk, fresh lemon juice, and zest until perfectly smooth and thick. The aroma is guaranteed to make your mouth water.

Step 5: Assemble and Top

As soon as your crust comes out of the oven (it should be hot!), pour the lemon filling over the base and use a spatula to spread it to the edges. Sprinkle the remaining oat crumble evenly over the lemon layer—it will look rustic, and that’s just what you want for these homey bars.

Step 6: Bake and Cool

Return the pan to the oven for another 22 to 25 minutes, until the edges are lightly golden and the top is set. Remove to a wire rack and let the bars cool completely in the pan; patience here pays off with neat slices. Once cool, use the parchment overhang to lift out, cut into squares, and marvel at your beautiful Lemon Oatmeal Crumble Bars!

How to Serve Lemon Oatmeal Crumble Bars

Garnishes

A dusting of powdered sugar adds a magical, snowy touch that gently plays up the lemon’s brightness. For extra flair, try a few coils of lemon zest curls on each square or sprinkle with additional oats for a rustic look. If you’re feeling generous, a dollop of whipped cream on a chilled bar is pure lusciousness.

Side Dishes

Pair Lemon Oatmeal Crumble Bars with a mug of chamomile tea, an iced coffee, or even a cold glass of milk—they never fail to complement each other. These bars also make a wonderful addition to a dessert platter, starring alongside fresh berries or a handful of juicy grapes. If you’re hosting brunch, set them with Greek yogurt and fruit salad for a sweet finish.

Creative Ways to Present

For parties or showers, cut the bars into bite-sized pieces and serve in cupcake liners for easy grabbing. Stack squares on a pretty cake stand for height, or drizzle a simple glaze over the top for a glossy finish. Want to go picnic-perfect? Wrap individual bars in parchment and twine—they travel exceptionally well and look absolutely charming.

Make Ahead and Storage

Storing Leftovers

Once cooled and sliced, cover leftover Lemon Oatmeal Crumble Bars and store them at room temperature for up to two days. If your kitchen is warm or you want to keep them super fresh, pop them in the fridge, tightly covered, where they’ll keep beautifully for up to a week.

Freezing

Lemon Oatmeal Crumble Bars freeze like a dream! Arrange the fully cooled bars in a single layer, separated by parchment, in an airtight container or zip-top bag. They’ll stay delicious for up to three months; just thaw overnight in the fridge or on the counter before serving.

Reheating

While these bars are designed to be served at room temperature or chilled, you can gently rewarm them if you want a gooey middle and fragrant oat topping. Zap individual squares in the microwave for 10 to 15 seconds or warm larger portions in a low oven for a few minutes—just until slightly soft and aromatic.

FAQs

Can I use bottled lemon juice instead of fresh?

Fresh lemon juice delivers that vibrant, natural tang that really shines in Lemon Oatmeal Crumble Bars. Bottled juice can taste flat or even a bit bitter, so if possible, go with fresh. The zest is equally important for maximum citrus flavor!

What kind of oats work best?

Old-fashioned rolled oats give the bars a chewier, heartier texture, while quick oats make the crumb slightly finer and more uniform. Both work well, so choose based on your texture preference. Avoid instant oats—they’ll turn mushy.

Is it okay to double the recipe for a crowd?

Absolutely! Simply double all the ingredients and bake the bars in a 9×13-inch pan. You may need to add a couple of minutes to the baking time, so keep a close watch on the color of the crust and topping.

Why does my crust mixture seem dry and crumbly?

It’s totally normal for the oat crust and topping to look dry and crumbly before baking—that’s what creates the delicious, tender crumb. After baking, the butter melts and binds everything together, so don’t worry if it seems loose at first.

Can I make Lemon Oatmeal Crumble Bars gluten-free?

You can! Swap the all-purpose flour for your favorite one-to-one gluten-free flour blend, and be sure to use certified gluten-free oats. The finished bars will still be crisp, crumbly, and full of zingy lemon flavor.

Final Thoughts

If you’re searching for a dessert that tastes like sunshine and homey comfort in a single bite, these Lemon Oatmeal Crumble Bars are it. They’re easy enough for a weekday treat and pretty enough to impress at any gathering. Give them a try and watch these sweet-tart, buttery bars become a craving in your household!

Lemon Oatmeal Crumble Bars Recipe

★★★★★

5 from 5 reviews

Author: Zoe
Total Time: 45 minutes
Yield: 12 bars 1x
Diet: Vegetarian

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Description

These Lemon Oatmeal Crumble Bars are a delightful treat that combines a buttery oatmeal crust and topping with a tangy lemon filling. Perfect for citrus lovers!

Instructions

Preheat oven and prepare pan: Preheat oven to 350°F (177°C) and line an 8-inch square pan with parchment paper.
Make the crust/topping: Beat butter and brown sugar, add vanilla, then mix in flour, baking powder, salt, and oats until crumbly. Press a little more than half of the mixture into the pan and bake for 12 minutes.
Prepare lemon filling: Whisk together sweetened condensed milk, lemon juice, and lemon zest until thick.
Assemble and bake: Spread lemon filling over pre-baked crust, sprinkle remaining crumble mixture on top, and bake for 22-25 minutes until set.
Cool and serve: Cool bars completely, then lift out using parchment paper, cut into squares, and store as desired.