Shoofly Pie

Name: Shoofly Pie
Ingredients: 1 9-inch pie crust, use your favorite; 1 egg white mixed with 2 teaspoons of water; 1 cup all-purpose flour or 1/2 cup each of brown and white rice flour; 2 tablespoons unsalted butter; A two-finger pinch of kosher salt; 3/4 cups dark brown sugar (muscovado is great for this); 1/2 cup molasses; 1/4 cup dark corn syrup; 3/4 cups boiling water; 3/4 teaspoons baking soda; 1 egg, beaten