For the brownies: blend together yogurt, milk, sugar and egg in a medium bowl. In a small bowl stir together cocoa, protein powder, baking powder, and flour.
Gently stir dry into wet until just incorporated and pour into a greased 8x8 inch pan.
Bake for about 20-25 minutes. Don’t over bake, err on the side of under baking.
For the frosting: In a small bowl blend together all ingredients, spread on top of cooled brownies and serve.
Notes
If you don’t want to use Splenda, substitute in ½ cup white sugar in brownies and to taste in frosting.