Preheat oven to 350 degrees. Place the pie shell or dish on top of a baking sheet.
Melt butter in a large saucepan over medium heat. Add leeks, sausage, and a sprinkle of salt and pepper, and cook until leeks are soft, about 10 minutes.
Meanwhile, whisk eggs, half-n-half, salt, pepper, and garlic powder. Set aside.
Once leeks and sausage are done, spoon them into the bottom of the pie shell, and pour the egg mixture over top. Lastly, crumble in the goat cheese. Carefully place the baking sheet onto the middle rack and cook for 40 minutes. Let rest for 10-15 minutes before serving.