Add eggs, cocoa powder, vanilla, vinegar, flour, a pinch of salt, and red food coloring. Whisk until smooth and pour into prepared pan. In a separate bowl, mix cream cheese, vanilla, sugar, and eggs.
Spoon the cream cheese mixture on top of brownie batter and swirl. If adding fruit jam, swirl in now too. Bake for 30-35 minutes. Remove from oven and allow to cool, then cut into hearts.
Top each brownie heart with melted white chocolate, like frosting, and allow to set. Use melted red candy melts to draw messages on top of the brownies. Allow to harden.