1. Heat oven to 325 degrees . Place paper liners in cups of mini muffin pans (36 total).
2. In a small bowl, whisk together flour, cocoa, baking powder, baking soda and salt.
3. In a large bowl, beat together butter and sugar. Beat in eggs, one at a time, beating well after each addition. Beat in yogurt. On low, beat in half the flour mixture. Pour in 2/3 cup water and beat on low until blended. Scrape down side of bowl. On low, beat in remaining flour mixture.
4. Divide batter among prepared cups. Bake at 325 degrees for 19 minutes. Cool completely. Frost and decorate as desired.