Preheat oven to 180°C (350°F). Line an 8x8-inch baking pan with parchment paper.
Melt the chocolate in the microwave. Let it cool, then whisk in yogurt and sugar.
Stir in flour, cocoa powder, and baking soda. Add milk and mix until combined.
Fold in chocolate chips, if using, and spread the batter into the prepared pan.
Bake for 25-30 minutes. Let cool before slicing.
Notes
* I used vanilla coconut Greek yogurt. Any non-fat or reduced fat yogurt works. TO STORE: Yogurt brownies will keep well at room temperature, in a sealed container. Be sure to lay a sheet of paper towel on top, to keep them super moist and fudgy. They will keep well for up to 5 days. To keep them longer, store them in the refrigerator. TO FREEZE: Brownies are freezer friendly and can be stored in the freezer for up to 6 months. Thaw overnight in the refrigerator or at room temperature.