No bake Chocolate Eclair Cake

1 box (3.4 oz) instant vanilla pudding mix
3 cups cold milk
1 container (8 oz) frozen whipped topping, thawed (like Cool Whip)
1 box graham crackers (about 16–20 sheets)
For the Chocolate Glaze:
1/2 cup unsalted butter
1/4 cup unsweetened cocoa powder
1 cup granulated sugar
1/4 cup milk
1 teaspoon vanilla extract
Optional Toppings:
Chopped nuts (like almonds or pecans)
Sprinkles
Shaved chocolate
Step-by-Step Instructions