Add the granulated sugar and eggs to a large mixing bowl. Whisk to combine. Add in the maple syrup (or corn syrup), melted butter, vanilla extract, and salt. Whisk to combine. Pour into the unbaked pie crust and place onto a rimmed baking sheet (optional).
In a medium mixing bowl, stir together the broken pretzels, 3 tablespoons melted butter, and the 2 tablespoons granulated sugar. Sprinkle over the top of the pie filling.
Bake in the oven for 1 hour. Cover the pie with foil after 30 minutes to prevent the top from becoming too brown.
Remove from the oven and cool completely on a wire rack before slicing and serving.
Notes
Storage Tips:
To store: Store it covered in the refrigerator for 3 to 4 days.
To freeze: Wrap the pie entirely in foil, wrapping it entirely around the top and bottom of the pie. Place into a freezer-safe zip-top bag and freeze for up to 3 months. Thaw in the refrigerator before serving.
Recipe Variations:With Oats: Use 1 1/2 cups rolled oats in place of the pretzels in the recipe. Omit the 3 tablespoons melted butter and 2 tablespoons granulated sugar from the recipe. Stir the rolled oats into the pie filling mixture and pour into the unbaked pie crust. Bake for 30 minutes at 350º F. With Oats and Coconut: Use 2/3 cup rolled oats and 2/3 cup shredded coconut in place of the pretzels in the recipe. Omit the pretzels, 3 tablespoons melted butter, and 2 tablespoons granulated sugar from the recipe. Stir the rolled oats and shredded coconut into the pie filling mixture and pour into the unbaked pie crust. Bake for 30 minutes at 350º F.