Slice and shred zucchini, and set slices aside for topping. In a fry pan, cook bacon till crisp. Cool and crumble. Wash and thinly slice the tender white part of the leeks, after discarding the tough green tops. Drain bacon grease from pan. Over medium heat, saute leeks in remaining bacon fat, till slightly caramelized. Shred Gouda cheese and set 1/4 cup aside.
In a medium mixing bowl, whisk eggs, half and half, salt, ground mustard, and garlic powder together. Add shredded zucchini, bacon, leeks, and 2 cups of cheese, and combine well. Pour into prepared pie shell. Top with slices of zucchini, remaining Gouda cheese and a sprinkle of paprika.
Bake in 350°F/175°C oven for 50-55 minutes. Watch carefully and if the crust is getting too brown, loosely cover with a sheet of foil. When finished baking the crust should be golden brown and the filling should be set. Let cool for 5 minutes before cutting and serving. Makes 6 to 8 servings.