Place the butter, cream cheese, and sugar in a large mixing bowl and beat until pale and fluffy.
Add the flour and cocoa, and mix until blended.
Stir in the red food coloring, buttermilk, and vanilla, and refrigerate the dough for about 1 hour.
Roll about a tablespoon of dough into a ball and shape into a teardrop. Cut a mini marshmallow in half with scissors, and place the cut end of the marshmallow on the tippy top of the teardrop. Place the cookie dough truffles on a parchment-lined baking sheet and refrigerate.
Place the white chocolate in a small bowl and microwave for 30 seconds at 100% power. Stir. Microwave for another 20 seconds, or until just a few lumps remain. Stir the white chocolate until smooth.
Place the coconut on a small plate. Dip the bottom of each truffle into the melted white chocolate, and then immediately into the coconut. Place on a parchment-lined baking sheet and chill until the white chocolate is set.