2 teaspoons + ½ cup butter, divided
3 tablespoons tapioca flour
2 tablespoons potato starch
2 whole eggs + 2 egg whites, room temperature
4 oz. semi-sweet chocolate, coarsely chopped (Ghirardelli recommended)
1 cup powdered sugar
2 tablespoons coffee, room temperature **
1 teaspoon vanilla extract
⅛ teaspoon salt
** Very strong black tea may be substituted for coffee.