Bell Pepper Sauce with Sausages

I'm trying to cook through my cookbooks a little bit more this summer and this recipe made the cut for being quick and easy and taking advantage of the bell peppers that are on sale right now. I scaled the recipe in half and had enough for 3 servings, but the original is included below. The original calls for red and yellow peppers, but I only used red.

One year ago: Arugula, Strawberry, and Caramelized Pear Salad

Bell Pepper Sauce with Sausages (from Essentials of Classic Italian Cooking)

Ingredients
3 bell peppers (1 red, 2 yellow or all red)
4 tbsp extra virgin olive oil
2 tbsp chopped onion
4 sweet Italian sausages, cut into 1/2" pieces, about 1 1/2 cups
salt
black pepper
1 cup canned plum tomatoes drained and cut up (I used without draining or cutting)
680g penne
1 tbsp butter
2/3 cup grated parmigiano-reggiano

1. Split the peppers into 4 sections, discard seeds and cores. Peel if desired. Cut into 1" square pieces.
2. Put olive oil and chopped onion in a saute pan and turn heat to medium high. Cook and stir until onion becomes a pale gold.
3. Add sausages and cook for 2 minutes, then add peppers and cook for 7 or 8 minutes. Add salt and pepper.
4. Add tomatoes to pan and cook at a lively simmer for 15 - 20 minutes, until oil floats free of tomatoes.
5. Empty contents of pan over cooked drained pasta and toss thoroughly.
6. Add butter and grated Parmesan, toss one more time, and serve at once.