Roast, peel and seed peppers .
Place peppers, garlic, pine nuts, chilli flakes, vinegar and oil in a food processor; pulse until smooth.
Add salt and pepper to taste.
Meanwhile, cook pasta in a large pot of boiling, salted water, until firm to the bite.
Drain, reserving 1/2 cup pasta water.
Return drained pasta to the warm pasta pot and add red pepper pesto.
Toss well to coat, adding reserved water as needed.
Serve immediately with parmesan.