Lightly grease 8 x 8 dish and set aside. In the top of a double boiler, melt chocolate chips with butter into smooth. Remove from the heat and add graham crumbs, coconut flakes and walnuts; stir until well blended. Transfer mixture to prepared dish, pressing down to the bottom. Chill bottom layer for 30 minutes.
In a large bowl, combine sugar, butter, cornstarch, peppermint extract, sea salt, milk and food coloring. Beat ingredients until smooth. Add more natural green food coloring until desired color; process until completely combined. Spread evenly over the cooled base and refrigerate for 30 minutes.
In the top of a bain-marie, add dark chocolate chips & mint chocolate &, butter and vanilla extract. Stir until mixture is melted and smooth – DON’T make it hot. Spread evenly topping over mint layer. Cool for about 15 minutes and cut into squares. Makes 12 bars.