Preheat oven to 350°F (175°C) and line an 8x8-inch pan with parchment paper.
In a bowl, mix melted butter and sugar until glossy.
Add eggs and vanilla extract, stirring to combine.
Whisk cocoa powder, flour, salt, and baking powder into the wet ingredients until smooth.
Pour brownie batter into the prepared pan and spread evenly.
Beat cream cheese and sugar until fluffy. Add egg and vanilla extract, mixing until smooth.
Spread the cream cheese mixture evenly over the brownie batter in the pan.
Drop spoonfuls of raspberry preserves on top and gently swirl with a knife to marble.
Bake for 28 to 32 minutes until the center is just set.
Cool completely, then chill for 30 minutes for clean cuts.
Use a heart-shaped cookie cutter to cut brownies into individual hearts.