Oat and Amaranth-Crusted Ham and Cheese Quiche

1. Place the rack in the center of the oven and preheat to 350°F. Butter a 9-inch pie plate. Set aside.
2. To make the crust, grind the oats into a fine flour in a spice grinder or blender. Transfer to a medium-sized bowl.
3. Heat a large skillet. Add the amaranth and stir constantly until the seeds begin to pop and smell toasty, about 3 minutes. Remove from heat and pour into a small bowl to cool. Transfer half to a spice grinder or blender and grind them into a fairly fine flour. (The amaranth flour may be slightly coarser than the oat flour.) Transfer the flour to the bowl with the oat flour, and then grind the second batch of popped amaranth.
4. Add the second batch of amaranth flour and the salt to the bowl. While stirring, gradually add the melted butter. Stir in 2 Tbsp. of the cold water. Add more water, if needed, to create a dough that holds its shape when pressed together.
5. Press the dough evenly, about ¼-inch thick, onto the bottom and up the sides of the pie plate. Bake for 15 minutes. Liberally coat the pie crust with the egg white, taking care to fill in any cracks. Return to the oven for 1 minute. Set on a cooling rack. Keep the oven on.
6. While the crust is cooking, prepare the filling: in a bowl, mix the eggs, yolk, milk, mustard, rosemary, and salt.
7. Distribute the Gruyère AOP and ham on the pie crust. Pour the egg mixture on top. Bake until the top is browned and the center is set, 30 to 40 minutes. Let cool on a rack for 5 to 10 minutes before slicing into portions.

Variations:  Use olive, corn, or peanut oil instead of melted butter for the crust. For vegetarians, omit the ham and add 3 Tbsp. chopped sun-dried tomatoes and/or pitted olives.