Start with your favorite brownie recipe, or ready-mix box, and make according to directions. Then add a box of your favorite flavor instant pudding mix.
Stir in a various assortment of nuts, chocolate chips, butterscotch chips, peanut butter chips, crushed candy pieces, or mini marshmallows as you like.
The batter will be super-thick. Try not to eat it all as you scrape it into an oiled pan.
Drizzle on sundae toppings like hot fudge, caramel sauce, marshmallow fluff, butterscotch, etc. Drag a fork through if you like to be artsy, but don’t stir.
Bake according to your recipe’s directions, or until they seem done. The more sundae toppings you add, the gooier they’re going to be, even fully cooked.
They’re best warm, but keep for several days. Serve with ice cream if you dare.