Steps:

• Heat oven to 350°F. Grease and flour 15x10x1-inch baking pan or 13x9-inch pan. In large bowl, combine all cake bar ingredients; stir until well blended. Pour into greased and floured pan.
• Bake at 350°F. until toothpick inserted in center comes out clean. For 15x10x1-inch pan, bake 20 to 30 minutes; for 13x9-inch pan, bake 25 to 35 minutes.
• In small saucepan, combine sugar, milk and margarine. Bring to a boil. Boil 1 minute, stirring constantly. Remove from heat; stir in chocolate chips until smooth. Pour and spread over warm bars. Cool 1 1/4 hours or until completely cooled. Cut into bars.

Steps:

• Preheat oven to 325 degrees F (165 degrees C).
• Beat cake mix and butter with an electric mixer on low speed in a bowl until crumbly, 3 to 5 minutes. Set aside 1 cup for topping.
• Press remaining crumb mixture into bottom of an ungreased 9x13 inch pan.
• Place in preheated oven and bake until edges begin to crisp, about 10 minutes. Remove from the oven and cool slightly.
• Beat cream cheese and frosting with an electric mixer on medium speed in a bowl until smooth, 3 to 5 minutes.
• Drop eggs one at a time into the cream cheese mixture and beat until blended, 2 to 3 minutes.
• Pour in 6 drops green food coloring, or more for a darker color; beat until color is blended, about 2 minutes.
• Beat in creme de menthe candy flavoring until thoroughly blended, about 2 minutes. Taste and add more flavoring if needed.
• Pour batter over the chocolate crust in the 9x13 pan.
• Sprinkle 1 cup reserved crumb mixture over cheesecake batter.
• Top with 1 cup chocolate and mint morsels; reserve remaining morsels for finishing touches.
• Place the pan in the preheated oven and bake until set, 42 to 45 minutes.
• Remove pan from oven and cool completely.
• Cover and refrigerate until chilled, at least 2 hours.
• Pour reserved chocolate and mint morsels into a small microwave-safe bowl. Microwave morsels in 45 second intervals; stir until completely melted and smooth.
• Pour melted chocolate into a resealable plastic bag.
• Clip a small bottom corner of the bag. Gently squeezing the bag, drizzle melted chocolate over the cooled cake through the clipped corner.
• Cut cake into bars to serve.