Skinny Chocolate Peanut Butter Swirl Cupcakes

INGREDIENTS

large *very* ripe bananas, mashed (about 1 cup - the riper, the better)

1/2 cup

granulated sugar

large egg whites

3/4 cup

greek yogurt (low fat or nonfat, vanilla or plain, or regular yogurt)

2 tsp

vanilla extract

1/2 cup

whole-wheat flour (measured correctly)

1/2 cup

all-purpose flour

1/2 cup

unsweetened cocoa powder

1/2 tsp

salt

1 tsp

baking soda

1 tsp

baking powder

1/2 cup

dark chocolate chips (or semi-sweet)

1/4 cup

creamy peanut butter, melted (natural peanut butter is OK, do not use powdered peanut butter)

1/3 cup

peanut butter chips (optional)