Heat the oil in a frypan over medium heat. Add the onion, garlic and sage, season, then cook, stirring occasionally, for 20 minutes or until the onion is golden brown. Add the balsamic and cook for a further 5 minutes or until caramelised.
Meanwhile, cook the pasta in a large pan of boiling salted water according to the packet instructions, adding the peas for the final 3 minutes of cooking time, until the pasta is al dente and peas are tender.
Drain the pasta and peas and return to the pan. Add the caramelised onion (or onion marmalade if using) and toss to combine. Serve topped with parmesan.
Recipe courtesy of taste.com.au
Serving size 4