6 tablespoons butter, softened
2/3 cup granulated sugar
1/4 cup milk
1 1/2 teaspoons baking powder
1/2 teaspoon salt
1 3/4 cups unsifted all-purpose flour
1 teaspoon vanilla extract
1 large eggs
2 tablespoons instant coffee dissolved in
    2 tablespoons boiling water
1 tablespoon coffee-flavored liqueur (optional)
3/4 cup chocolate chips

Preheat oven to 375 degrees F. Grease a 6-muffin pan.

In a large bowl, beat butter and sugar at medium speed of electric mixer until light and fluffy. Beat in egg, vanilla extract, dissolved coffee granules and coffee liqueur until blended.

In medium bowl, combine flour, baking powder and salt. Add flour mixture to butter mixture alternately with milk, beating just until combined. Fold in chocolate chips. Divide batter among muffin pan cups.

Bake 25 to 30 minutes or until centers spring back when lightly pressed.

Serve warm.