Heat oven to 350°. Make the crust first: Whisk together 1-½ cups flour and ⅓ cup maple sugar; then cut in softened butter. Using a standing mixer, or a fork if you’re working by hand, blend until the mixture resembles coarse meal, dry and crumbly. Press the mixture into the bottom of a greased 8- or 9-inch square pan. Bake 15 minutes.

To make the topping, combine ¾ cup maple syrup, ½ cup maple sugar, beaten egg, melted butter, cream, vanilla, 1 tablespoon flour, and salt. Beat well; then stir in nuts. Pour batter carefully over half-baked crust.

Return crust and topping to the oven. Bake until set, about 35 minutes. Cut into small bars and remove from pan to cool.