Preheat oven to 350 degrees. Add sliced almonds to a food processor then process into fine crumbs. Add to a medium-sized bowl with graham cracker crumbs and sugar then mix well to combine. Add butter then mix well to combine. Pour mixture into a 9" pie pan or tart pan then press into an even layer on the bottom and slightly up the sides. Poke the bottom with a fork then bake for 8-10 minutes or until golden brown. If crust has puffed up too much in the center after baking, use the bottom of a measuring cup to gently press it back down. Set aside to cool.

Add chocolate chips and vanilla to a medium-sized bowl then place a fine mesh sieve on top and set aside. Add egg yolks, sugar, cornstarch, and cocoa powder to another medium-sized bowl then whisk until smooth. Heat milk in a small saucepan over medium heat until it just starts to simmer then pour half of it into the egg yolk mixture while whisking vigorously. Turn the heat to low then pour the egg yolk/milk mixture back into the saucepan and whisk to combine. Switch to a spatula then cook until filling has thickened, 1 minute.

Pour filling into the fine mesh sieve set atop the bowl of chocolate chips then press with a spatula to strain out any pieces of cooked egg. Stir until chocolate chips have melted then pour filling into the crust and smooth the top. Let cool for 10 minutes at room temperature then cover with saran wrap and chill overnight. Slice then serve with whipped cream and berries if desired.