Prepare the Raspberry Filling : In a medium saucepan over medium heat, combine ¾ of the thawed raspberries, cornstarch, lemon juice, and sugar. Cook the mixture, stirring often, until it thickens and becomes glossy, about 5 minutes. Remove from heat, fold in the remaining raspberries, and allow it to cool.

Prepare the Brownie Batter: Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking pan and line it with parchment paper. In a large bowl, combine melted butter, brown sugar, granulated sugar, and vegetable oil, whisking until smooth. Add powdered sugar, cocoa powder, eggs, vanilla extract, and salt, whisking until fully blended. Slowly fold in the flour, mixing gently until just combined. Avoid overmixing.

Make the Cheesecake Layer : In a medium bowl, beat cream cheese, granulated sugar, and vanilla extract until smooth and creamy. Set aside.

Assemble the Layers: Evenly spread ¾ of the brownie batter into the prepared pan. Carefully layer the cheesecake mixture on top of the brownie batter. Add spoonfuls of the raspberry filling over the cheesecake layer, distributing it evenly.

Bake : Bake in the preheated oven for 50–55 minutes, or until the center is set and the edges begin to pull away from the pan.