Step 1: Prep Your Pan
Preheat your oven to 350°F. Line an 8-inch square baking dish with foil or parchment paper and spray with non-stick spray.

This step is important—not only for easy cleanup but also to help remove the bars cleanly after baking.

Step 2: Make the Crust and Crumble Mixture
In a large microwave-safe bowl, melt the butter. Add the flour, oats, both sugars, and salt. Stir until everything is combined into a crumbly, sandy mixture.

Set aside about 1 heaping cup of the mixture. This will be used later for the topping.

Press the rest of the mixture into the bottom of your prepared pan. Use a spatula or your fingers to pack it down into an even, tight crust.

Step 3: Make the Strawberry Layer
In the same bowl, toss together the strawberries, sugar, lemon juice, and cornstarch. Don’t worry if the sugar doesn’t dissolve completely—it will melt in the oven.

Spread the strawberry mixture evenly over the crust.

Take your reserved crumble mixture and sprinkle it over the top. I like to squeeze small handfuls together to form larger crumbles—it adds great texture once baked.

Step 4: Bake and Cool
Bake the bars at 350°F for about 50 minutes, or until the top is lightly golden and the edges are bubbling.

The topping should look dry and slightly crisp. If your strawberries are very juicy, baking may take closer to 55 minutes.

Remove from the oven and let the bars cool in the pan for at least 1 hour. This helps them set up and makes slicing much easier.

Once cool, lift them out of the pan and slice into squares. Serve at room temperature or chilled.