In a sauté pan, sweat the onion, chili flakes and garlic in the butter.
When the butter is browned, turn off the fire and deglaze the pan with the amaretto. Add the sausage and sage. Add the pie filling and whisk. Add the pasta to the pan and finish by squeezing in some lemon juice.
(Optional: Dry the pie crust in a low oven. Crumble and sprinkle over the pasta.)