Preheat the oven to 350 degrees F. Lightly spray a 10-inch loose-bottom pie pan with nonstick baking spray, then set it on a baking sheet.
Add 3 cups salted pretzels to a food processor and process until you have fine, even crumbs, about 20 to 30 seconds. Stop before they turn to dust.
Add 1/2 cup plus 2 tablespoons unsalted butter to a saucepan over medium heat. Melt it, then keep heating, swirling the pan often, until the butter foams and the milk solids turn golden brown and smell nutty, about 5 minutes. Remove from the heat.
In a bowl, combine the pretzel crumbs and 1/3 cup granulated sugar.
Pour the warm browned butter over the top and mix until evenly moistened.
The mixture should hold together when squeezed. If it doesn't, add a little extra melted butter (plain is fine for this), one tablespoon at a time, until it comes together.
Press the pretzel mixture firmly across the base and up the sides of the pan, compacting it especially where the base meets the sides.
Bake for 12 to 15 minutes, until deeply golden, dry to the touch, and fragrant. If the crust puffs slightly, gently press it back down while still warm. Cool completely before filling.
Notes
Make ahead up to 2 days; cool completely, wrap, and hold at room temperature. No-bake option: press into the pan and chill at least 1 hour instead of baking (sets softer).