Heat oven to 400°F.

Grease bottoms only of 12 regular-size muffin cups with shortening or cooking spray, or place paper baking cup in each muffin cup.

In medium bowl, mix flour, cocoa, baking powder and salt.

In large bowl, beat brown sugar, milk, oil, 1 tablespoon coffee granules and the egg with fork or whisk.

Stir in flour mixture just until flour is moistened.

Fold in chocolate chunks.

Divide batter evenly among muffin cups.

Bake 18 to 20 minutes or until toothpick inserted in center comes out clean.

Immediately remove from pan to cooling rack.

Spoon frosting into a small microwavable bowl; stir 2 teaspoons espresso powder into frosting.

Heat on High 10 seconds or until frosting can be stirred to drizzling consistency.

Drizzle over warm muffins.

Serve warm or cool.