1. Heat oven to 325°F. Grease and flour 9x5x3-inch loaf pan.
2. Beat butter, cream cheese and sugar in medium bowl until fluffy. Add eggs and vanilla; beat well. Stir in flour and baking powder; stir in 1 cup mint chocolate chips (reserving the remainder for glaze) and green food color, if desired. Pour batter into prepared pan.
3. Bake 45 to 50 minutes or until cake pulls away from sides of pan. Cool 10 minutes; remove from pan. Cool completely on wire rack. Prepare MINT CHOCOLATE CHIP GLAZE; spread over top of cake, allowing glaze to run down sides. Cool completely. About 12 servings.
MINT CHOCOLATE CHIP GLAZE: Place remaining 2/3 cup mint chocolate chips and 2 tablespoons shortening (do not use butter, margarine, spread or oil) in small microwave-safe bowl. Microwave at MEDIUM (50%) 30 seconds; stir. If necessary, microwave at MEDIUM an additional 15 seconds at a time, stirring after each heating, just until chips are melted when stirred.