To prepare bottom layer, weigh or lightly spoon flour into a measuring cup; level with a knife.
Combine flour and salt; stir with a whisk.
Combine granulated sugar, egg substitute, cup melted butter, 2 tablespoons water, vanilla, eggs, and chocolate syrup in a medium bowl; stir until smooth.
Add flour mixture to chocolate mixture, stirring until blended.
Pour batter into a 13 x 9 inch metal baking pan coated with cooking spray.
Bake at 350 for 23 minutes or until a wooden pick inserted in center comes out almost clean. Cool completely in pan on a wire rack.
To prepare mint layer, combine powdered sugar, cup melted butter, and next 3 ingredients (through food coloring) in a medium bowl; beat with a mixer until smooth.
Spread mint mixture over cooled cake.
To prepare glaze, combine chocolate chips and 3 tablespoons butter in a medium microwave-safe bowl. Microwave at HIGH 1 minute or until melted, stirring after 30 seconds.
Let stand 2 minutes.
Spread chocolate mixture evenly over top. Cover and refrigerate until ready to serve.