1. Make the Raspberry Filling:
Thaw the raspberries and reserve 3 tablespoons of juice to mix with the cornstarch.
Using a fine sieve, strain half of the raspberries to remove the seeds, pushing as much of the raspberry pulp through as possible.
Combine the sieved berries with the remaining whole berries and any juice.
In a small saucepan, mix the reserved 3 tablespoons of raspberry juice with the lemon juice, cornstarch, and granulated sugar. Bring the mixture to a boil, stirring continuously.
Once boiling, add the raspberry mixture and bring it to a simmer. Simmer for one minute while continuing to stir, then remove from heat.
Transfer the mixture to a bowl, cover, and refrigerate until completely cooled, about 2-3 hours or overnight.
2. Make the Brownie Batter:
In a large mixing bowl, combine the melted butter, light brown sugar, and granulated sugar. Mix for about a minute to help dissolve the sugars.
Add the vegetable oil, powdered sugar, and cocoa powder, mixing until all lumps are incorporated.
Add the eggs, vanilla extract, and salt, mixing thoroughly before stirring in the flour until just combined.
3. Make the Cheesecake Layer:
In a separate mixing bowl, beat the softened cream cheese with a hand mixer until completely smooth.
Add the granulated sugar and vanilla extract, mixing until well combined.
4. Assemble the Raspberry Cheesecake Brownies:
Preheat the oven to 350°F (176°C). Line a 10×10 inch baking pan with parchment paper and lightly spray with cooking spray.
Pour the brownie batter into the prepared pan, spreading it evenly.
Dollop the cream cheese mixture over the brownie batter.
Spoon about 1 to 1 ½ cups of the raspberry filling over the cream cheese layer.
Swirl the cream cheese and raspberry filling into the brownie batter using a knife or skewer to create a swirl pattern. Be careful not to overmix.
Bake for 40-45 minutes, or until the edges are set and the center has a slight wobble.
Allow the brownies to cool completely before cutting and serving.