This festive Christmas Bark is easy and delicious! Layers of graham crackers, brown sugar toffee, peanut butter, and chocolate make this an addictive holiday treat.
Preheat oven to 400°F. Line a 13x18 rimmed baking sheet with foil and spray it with nonstick spray. Lay the graham cracker sheets in a single layer, side by side in the pan, breaking pieces as needed to fill the pan.
Place butter and brown sugar in a medium saucepan. Bring the mixture to a boil, and boil for 3 minutes, stirring occasionally. Carefully pour over the graham crackers. Use a rubber spatula to evenly spread the mixture over the graham crackers.
Place the pan in the oven for 4 minutes. Remove from the oven and pour the melted peanut butter on top (if using). Use a rubber spatula to evenly spread the peanut butter. Sprinkle with chocolate chips and place back in the oven for 1 additional minute, to melt the chocolate (the chocolate might still be in the shape of the "chips", but it should be soft enough to spread). Remove from the oven and use an offset spatula to evenly spread the melted chocolate. Allow to cool just slightly, then sprinkle the top with M&M’S and sprinkles.
Cool to room temperature, then transfer to the refrigerator to firm up completely. Once chilled, break the toffee into irregular pieces. Store in the refrigerator.