1 stick (8 tablespoons) unsalted butter, melted, plus more for buttering the dish
14 chocolate graham crackers
One 14-ounce can sweetened condensed milk
One 10-ounce bag mint chocolate chips
1 cup cocktail peanuts, coarsely chopped
2 cups mini marshmallows
1/2 cup red and green candy-coated chocolates, such as M&M’s
1/2 cup coarsely chopped candy canes
1/4 cup red and green sprinkles
Position an oven rack in the center of the oven and preheat to 350 degrees F. Line a 9-by-13-inch baking dish with foil, leaving a 2-inch overhang on both sides. Butter the foil.
Pulse the graham crackers into fine crumbs in a food processor. Add the melted butter and pulse to combine (the mixture should hold together when squeezed).
Transfer the mixture to the prepared baking dish and press it into the bottom in an even layer, using the bottom of a measuring cup to help. Pour the sweetened condensed milk over the crumbs. Sprinkle the chocolate chips, peanuts, marshmallows, M&M’s, candy canes and sprinkles over the condensed milk.
Bake until the sides are golden brown and begin to pull away from the baking dish, 30 to 35 minutes. Let cool completely, about 1 hour. Using the foil liner as handles, lift the bars out of the baking dish; remove the foil. Cut into 24 bars.