Melt chocolate and butter in a double boiler over hot, but not boiling, water, stirring often. Alternatively, melt chocolate and butter in a microwave-safe bowl in the microwave at 600 watts in 30 second intervals, stirring in between, until chocolate and butter are melted and smooth. Cool until barely warm.

Add sugar, eggs and vanilla to chocolate mixture and beat lightly with a rubber spatula until combined. Fold in flour.

Spread ¾ of brownie batter in prepared pan. Top with the cheesecake mixture and spread it to cover the entire surface of the brownie batter. Drop spoonfuls of remaining brownie batter and raspberry jam over the cheesecake layer and swirl the batters together with a butter knife, going back and forth across the pan. Don’t swirl too much or you’ll lose the marbled effect. Press fresh raspberries into the batter.

Bake brownies for 30 minutes. Remove from oven and cool completely in the pan on a wire rack. For best results, chill brownies for at least 2 hours before cutting into squares.

Store brownies tightly covered in the refrigerator for up to 4 days.