Preheat the oven to 350°F (175°C).

Butter and flour an 8" square baking pan; set aside.

In a food processor, process 8 tbsp.

of cubed and chilled butter, 1 cup flour, and 1/4 cup maple sugar until combined.

Transfer the mixture to the prepared pan and press evenly into the bottom.

Bake until lightly browned, about 15 minutes.

In a mixing bowl, whisk together the remaining 2 tbsp.

flour and 2/3 cup maple sugar.

Add the maple syrup, chopped walnuts, kosher salt, and lightly beaten eggs.

Mix until well combined.

Pour the mixture over the baked crust and bake until the filling is golden brown and set, about 30 to 35 minutes.

Allow to cool completely in the pan before cutting into squares and serving.