Heat oven according to brownie package instructions. Prepare an 8-inch square pan with a parchment paper sling.
Add brownie mix package and ingredients from the box to a large mixing bowl. Add McCormick® coffee and pure vanilla extracts and mix with a rubber spatula. Be sure not to overmix or they will become cake-like. Bake according to instructions on the box.
Remove brownies using the parchment paper sling and allow to cool and rest on a baking rack.
Mocha Frosting
Add shortening and butter to a medium-sized mixing bowl. Mix with an electric hand mixer until mixed. Add cocoa powder and the mixture is throughly mixed and cocoa brown colored. Add confectioner's sugar in batches and mix with your mixer. Frosting will look crumbly at this stage. Add milk 1 Tablespoon at a time and mix thoroughly. Mix until frosting is smooth and well combined, about 2 to 4 minutes. Refrigerate frosting until needed.
Cookie Dough
Cream butter and sugars in a mixing bowl with an electric hand mixer. Add milk and extracts and mix well. Add cocoa powder, flour and salt and mix with a rubber spatula. Add chocolate chips and stir to combine.
Assembly
Pick up brownies via the parchment paper sling and place back into the cooled baking pan. Tape parchment paper sides down. Add mocha cookie dough on top. Spray an offset spatula with baking spray and smooth the cookie dough over the brownies. Wipe spatula with a clean paper towel. Add mocha buttercream frosting to the top of the cookie dough layer. Smooth frosting with the offset spatula.
Cover and chill in the refrigerator for at least 60 minutes before cutting and serving.