Mushroom-and-Spinach Quiche in an Oat Crust

Oat flakes give the creamy filling of this quiche a crisp touch. It is perfect for breakfast or a light lunch.
Preheat the oven to 375 degrees.To make the crust, combine the oat flakes and oat bran; grind the butter using a pastry blender or 2 knives until the mixture resembles coarse flour. Add the water; stir until the dough is moist. Gently squeeze the mixture into a ball on waxed paper and cover with another waxed paper. Roll out the dough until it is coated, in a 10-inch circle.Remove 1 sheet of waxed paper and place the dough on a 9-inch pie dish greased with cooking spray. Remove the top sheet of waxed paper. Bake at 375 ° C for 7 minutes. Cool on a wire rack.To prepare the filling, place a medium-sized non-stick skillet covered with cooking spray over medium-high heat until it heats up. Add the leeks; simmer for 2 minutes. Add the mushrooms; saute for 5 minutes. Remove from heat; spoon into a bowl.Combine the milk and the following 8 ingredients (milk and spinach) in a blender and whisk until smooth. Add to the mushroom mixture and mix well. Pour over the prepared crust and sprinkle with Gruyere cheese. Bake at 375 ° C for 35 minutes or until a knife inserted in the middle comes out clean. Let stand for 5 minutes.