For perfectly smooth cheesecake, ensure your cream cheese and eggs are at room temperature to avoid lumps. Straining the raspberry sauce is key for a velvety, seedless swirl. When mixing the brownie batter, stir only until the flour streaks disappear to maintain a fudgy texture. These brownies can be made ahead; store them in an airtight container in the refrigerator for up to 4 days. For longer storage, wrap individual hearts in plastic wrap and freeze for up to 3 months.