For the cookie crust, remove three or four cookies from the package, and set them aside for garnish (optional). Pulse the rest of the cookies in a food processor until the crumbs are uniform. You can also do this by placing the cookies in a bag and crushing them with a rolling pin. Melt the butter, sugar, and cocoa on the stove over medium heat. When it’s combined, mix 1/4 cup of the mixture into the egg to temper. Add egg mixture back to the chocolate mixture and stir over the heat until slightly thickened. Remove from heat and stir in cookie crumbs, almonds, and coconut. Press into a greased 8×8 or 9x9 baking pan. Refrigerate for about 20 minutes.

To make the caramel custard, beat the butter and custard powder until fluffy. Beat in the powdered sugar until the custard is very fluffy and has doubled in size, about five minutes. Add the caramel sauce and salt. The custard should be fluffy but not runny. Pour the custard over the crust layer and refrigerate for about 15-20 minutes, or until the custard is cold and somewhat firm.

While the buttercream firms, heat the chocolate and butter over low heat until melted. Spread chocolate evenly over firm buttercream layer. Sprinkle chopped cookies, nuts, and coconut over the top, and refrigerate until chocolate is hardened. Cut into 12 bars or into bite sized pieces. Bring to room temperature before serving.