Preheat oven to 350F and grease an 8x8 inch baking pan.

For the cheesecake layer, puree raspberries and any juice that has accumulated. Place a fine mesh sieve over a bowl, and drain berry puree, pressing on solids to release as much juice as possible. Set aside.

In a large bowl, beat cream cheese and powdered erythritol until smooth. Beat in egg until well combined.

Add raspberry puree and raspberry liqueur or extract and beat until smooth and well mixed. Set aside.

For the brownie layer, melt butter, chocolate and cocoa powder together in a medium saucepan, stirring until smooth. Stir in erythritol and vanilla extract. Let cool 5 minutes.

Whisk in eggs, one at a time, until well combined. Spread mixture in prepared pan.

Pour cheesecake layer over top and use a knife to swirl layers together, bringing some of the brownie mixture to the surface.

Bake 20 to 22 minutes, or until sides are set and the middle is just barely jiggling. Remove from oven and let cool 20 minutes, then refrigerate until set, about 2 hours.