Preheat the oven to 350°F. Line a 9x9-inch pan with parchment paper.
Stir together the melted butter, brown sugar, ¼ cup of white sugar, and vanilla. Add the flour, baking soda, salt, and chocolate chips and mix until crumbly and combined. Press ⅔ of this mixture into the bottom of the prepared pan.
In a separate bowl, mash and muddle the raspberries, 2 tablespoons of white sugar, and cornstarch until combined. Spread over the bottom crust in the pan. Top with the remaining crumble mixture.
Bake in the preheated oven for 30-35 minutes or until golden brown around the edges. Let cool in the pan for 30 minutes before lifting out of the pan with the parchment paper. Let cool fully before slicing to serve.
Notes
You could use unsalted butter instead with an additional ½ teaspoon of salt added.
Thaw first if using frozen raspberries.
You could use semisweet chocolate chips, milk chocolate, dark chocolate, or even white chocolate.
Store fully cooled bars in an airtight container at room temperature for up to 3 days.