Step 1

Preheat the oven to 425°F. Line a baking sheet with aluminum foil or parchment paper.

Step 2

Place cut onions and garlic cloves on baking sheet. Drizzle with olive oil, sprinkle with salt and pepper. Roast in the preheated oven until tender and cut surface of the onion is golden brown, about 25-30 minutes.

Step 3

When cooked, transfer the onions and garlic to a food processor. Add the drained roasted red peppers and blend until everything is evenly combined and smooth. Set aside.

Step 4

Cook pasta in salted water according to package instructions.

Step 5

Transfer the pureed sauce to a large skillet and cook for a few minutes until the sauce bubbles. Season with salt and pepper to taste, then add milk to the skillet to thin out the pasta sauce. Whisk to combine.

Step 6

Drain the pasta and add it to the skillet. Toss to combine the pasta with the sauce to combine

Step 7

Serve with fresh parsley, if desired.