In a double boiler (over medium high heat) add 3/4 cup butter, sugar, cocoa, vanilla & egg, whisking until well combined. Stir until mixture reaches a custard like consistency (thickens slightly).
Stir in graham wafer crumbs and coconut mixing until combined. Press this mixture into an ungreased 8 x 8 or 9 x 9 square baking pan. Let cool completely.
Middle Mixture
In a large microwave safe bowl add 4 tbsp butter and Reese Peanut Butter Chocolate Spread. Microwave on medium - low in 30 second increments until completely melted.
Mix in icing sugar one cup at a time, alternating with 1 tbsp of milk until all icing sugar is incorporated. Spread evenly over your base and refrigerate until firmed up.
Chocolate Topper
In a microwaveable bowl melt butter and semi sweet chocolate on low in 30-40 second increments stirring in between. Continue until chocolate almost melted.
Remove from microwave and stir until remaining chocolate is completely smooth. Pour chocolate over squares and give a little shake to evenly distribute.
Refrigerate to harden top layer of chocolate before cutting and serving. Carefully slice and serve.