Potato Chip–Crusted Magic Bars

Preheat the oven to 350 °F. Butter a 9x13" baking pan, preferably metal, and line with parchment paper so it overhangs by a couple of inches on the long sides of the pan. In a food processor, pulse the potato chips with the flour until they resemble coarse bread crumbs. Pour in the 4 tablespoons butter and pulse until the chips are evenly moistened and finely chopped. Press the mixture into the prepared baking pan. Bake for about 15 minutes, until the crust is dry and very lightly browned. Let cool. Pour the sweetened condensed milk over the crust and tip the pan so it forms an even layer. Scatter the chocolate chips, coconut, and nuts on top and use a fork or the back of a spoon to press the ingredients into the sticky condensed milk. Bake for about 25 minutes, until the coconut is toasted and the condensed milk is lightly browned at the edges. Transfer to a rack and let cool. When the bar is cool, use the parchment paper to lift it out of the pan. Cut into any size squares you desire and serve.