Use a dark maple syrup (US grade B) for this recipe if you can. It has a much stronger maple taste than Grade A.
Ingredients

    1 9-inch pie shell, frozen for at least 30 minutes (see pie crust recipe)
    2 cups roughly chopped walnuts
    2 eggs, beaten
    1 cup maple syrup (dark robust)
    1 Tbsp dark rum (optional)
    1/2 teaspoon vanilla extract
    2 Tbsp melted butter
    2 Tbsp all purpose flour
    1/4 teaspoon salt
    1/8 teaspoon ground cinnamon
    1/8 teaspoon of ground nutmeg

    1 Make egg, maple syrup base: Preheat oven to 375°F. In a bowl, mix together the beaten eggs, maple syrup, rum (if using), vanilla extract, melted butter. Sprinkle with flour, salt, cinnamon and nutmeg. Whisk until smooth.

    2 Pour base over walnuts in pie shell: Spread the chopped walnuts over the bottom of a prepared pie shell. Pour the maple syrup egg mixture over the walnuts.

    3 Bake: Place the pie in the preheated oven on the middle rack. Place a cookie sheet on the rack underneath to catch any drippings from the pie crust.

    Bake at 375°F for 40-45 minutes. After about 20 minutes (about halfway through the baking), you may want to tent the pie crust edges with foil, or use a pie protector, so that the edges don’t get burnt.

    Don’t worry if the surface of the pie “cracks” while cooking. The pie filling will puff up while hot (because of the eggs), and then deflate while it cools.

    4 Cool: Remove from the oven and let cool completely before serving.