In a medium-sized pot over medium heat, melt salted butter, brown sugar, maple syrup, nutmeg, and salt; stir occasionally until the sugar is completely dissolved. Whisk together cream, eggs, and vanilla. Remove the sugar mixture from heat and let it cool while you roll out the pastry. Once cooled (it can still be warm), slowly whisk the sugar mixture into the egg mixture.
½ cup salted butter, 1 cup packed brown sugar, ½ cup maple syrup, ⅛ teaspoon nutmeg, ¼ teaspoon salt, ¼ cup cream, 10% mf. or higher, 2 eggs, ½ teaspoon vanilla