8 tablespoons (1 stick) unsalted butter, cubed and chilled, plus more for pan
1 cup plus 2 tablespoons all purpose flour, plus more for pan
1/4 cup plus 2/3 cup maple sugar
1 cup maple syrup
1 cup chopped walnuts
1/4 teaspoon kosher salt
2 eggs, lightly beaten
Preheat oven to 350F. Create a foil sling for your 8×8 inch baking tin and then butter and flour it; set aside.
In a food processor, pulse together butter, 1 cup flour, and 1/4 cup maple sugar until combined and looks like course sand; transfer to pan and press evenly into bottom. Bake until lightly browned, about 15 minutes.
Whisk together remaining flour and maple sugar with maple syrup, walnuts, salt, and eggs in a bowl; pour over baked crust. Return to the oven and bake until filling is golden brown and set, 30 to 35 minutes.
Cool completely on a wire rack. Using the foil sling, remove from pan and cut into 2″ squares.