Cook the pasta according to the package instructions and drain.
In a large bowl, mix together the cooked pasta, sliced smoked sausage, shredded cheese, cream of mushroom soup, milk, frozen peas, garlic powder, onion powder, salt, and pepper.
Pour the mixture into a casserole dish.
Bake in the preheated oven for 45 minutes, or until bubbly and golden brown on top.
Let it cool for a few minutes before serving.
Notes:
This casserole is great for leftovers and can be stored in the fridge for up to 3 days.