1/3 cup butter, at room temperature
1 cup brown sugar, firmly packed
2/3 cup unsweetened cocoa powder
1 tablespoon instant coffee granules
1 teaspoon baking soda
1 teaspoon ground cinnamon
2 large egg whites
1/3 cup vanilla yogurt
1-1/2 cups all-purpose flour
1/4 cup granulated sugar
Pre-heat oven to 350 F. Beat butter until light and fluffy; add brown sugar, cocoa powder, coffee granules, baking soda, and cinnamon. Beat until combined. Beat in egg whites and yogurt until combined. Stir in flour.
Place granulated sugar in a small bowl. Form dough into 1-inch balls and roll in sugar. Place balls 2 inches apart on an ungreased baking sheet. Bake for 8 to 10 minutes or until edges are firm. Allow to cool 2 minutes on baking sheet, then transfer to wire racks to cool completely.