Line an 8×8-inch baking dish with parchment paper. Set aside.
Melt 1 stick of cubed butter in a saucepan over medium heat. Add cocoa powder, salt, and brown sugar, remove pan from heat and whisk until mixture is well-blended.
Slowly whisk in beaten egg and mix constantly until egg is incorporated. Return pot to stovetop over medium heat and cook until chocolate mixture has thickened, stirring frequently, for up to 2 minutes.
Stir in vanilla extract, shredded coconut, chopped nuts, and graham cracker crumbs. Once blended, pour chocolate mixture into prepared baking dish. Cover with plastic wrap and refrigerate for 40 minutes.
Beat 5 tablespoons unsalted butter with heavy cream, and instant pudding powder until smooth. Stir in powdered sugar until creamy mixture comes together. Spread cream filling over top of the chocolate base layer and recover with plastic wrap. Return pan to the refrigerator for 20 minutes.
Melt chocolate chips with butter in a microwave safe bowl, cooking in short increments of time and stirring until melted and smooth. Add salt, if using, and stir until blended. Spread chocolate topping over top of the cream filling. Cover with plastic wrap and return to the refrigerator to chill for 30 minutes or until chocolate has completely set.
To serve, cut into squares. Store in an airtight container. If stacking your nanaimo bars, place a layer of parchment paper in between each layer.