Step 1

Cook the pasta according to package directions, under cooking by 1-2 minutes as it will continue to cook in the oven. Strain and set aside.

Step 2

Heat 2 tsp of oil in a pot over medium heat. Add the seitan sausage and cook until it's browning, ~3 minutes. Remove from the pan and set aside.

Step 3

Add the remaining 2 tsp of oil and add the onion with a pinch of salt. Sauté for 8-10 minutes until the onions are soft and lightly caramelized. As the onions cook, anything stuck to the bottom of the pan from cooking the sausage will lift up.

Step 4

Add the garlic, salt, herbs, and a pinch of red pepper flakes and cook for 1 minute. Add the tomatoes and sausage, cover the pot and bring the sauce to a simmer. Turn the heat to low and cook for about 15 minutes.

Step 5

Add everything to a blender and blend until very smooth.

Step 6

Preheat the oven to 375 ºF.

Step 7

Toss the pasta with about half of the sausage tomato sauce.

Step 8

In a casserole dish, add a couple of spoonfuls of sauce to the bottom of the dish, then add about 1/3 of the pasta. Top with about half of the remaining tomato sauce, then pour about 1/4 cup of the mozzarella sauce over that.

Step 9

Repeat and layer the next third of the pasta, the remaining tomato sauce, and the next ~1/4 of the mozzarella sauce. Next, top with the last of the pasta then smother with the remaining mozzarella sauce.

Step 10

Put the casserole dish in the oven and bake for 25-30 minutes, or until the cheese sauce has browned. Optional: turn on the broiler at the end for 2-5 minutes for further browning.