Preheat your oven to 350°F (175°C) and line an 8x8-inch baking pan with aluminum foil, lightly sprayed with cooking spray.

Melt the ½ cup of butter in a microwave-safe bowl for about 1 minute until fully melted.

Whisk together the melted butter, ½ cup granulated sugar, ¼ cup light brown sugar, and 1 teaspoon of vanilla extract for about 1-2 minutes until smooth.

Add 1 cup of all-purpose flour, ¾ cup of old-fashioned rolled oats, and a pinch of salt to the mixture, stirring gently until just combined.

Press the remaining mixture into the bottom of the prepared baking pan to form an even layer.

Spread 1 cup of raspberry preserves evenly over the pressed crust layer.

Sprinkle the reserved crumble mixture evenly on top of the raspberry preserves.

Bake for approximately 30 minutes, until edges are set and the top is lightly golden.

Let the pan cool on a wire rack for at least 2 hours before slicing into squares.