in a large zip-top bag and crush them with a rolling pin or the bottom of a heavy pan until you have mostly small pieces with a few larger bits for texture. You’re aiming for coarse crumbs, not a fine powder.
In a medium bowl, combine the crushed pretzels and melted butter. Stir until all of the pretzel crumbs are evenly coated and look slightly glossy; this is what helps them bake into a cohesive crust.
Transfer the buttered pretzel mixture to the prepared glass casserole dish. Press it firmly and evenly into the bottom of the dish using your hands or the bottom of a measuring cup to create a compact, level crust. Pay extra attention to the edges so they’re not thinner than the center.
Bake the pretzel crust in the preheated oven for 8–10 minutes, just until
