Preheat the oven to 180C/350F.

In a large baking dish add the sliced onion, olive oil, balsamic glaze, salt and pepper. Give it all a really good toss until everything is evenly distributed. Cover with foil and place in the oven for 1 hour and 10-15 minutes, or until the onions are very soft, sticky and sweet. Take them out a couple of times during to toss (this is important to release steam and prevent the ones on the outside from burning).

Slice the tip of the garlic to expose the cloves then drizzle with oil. Wrap in foil then place in the oven for 1 hour, or until deep golden, sticky and soft. Check progress after 45-50 minutes.

Towards the end of baking, add your pasta to salted boiling water and cook until al dente. Drain, reserving a cup of the pasta water.

When the baking dish is freshly hot out the oven, squeeze the garlic into the onions and mash it up, then mix in the sun dried tomatoes and mascarpone alongside a splash of the pasta water. Stir in the cooked pasta until combined then stir in the parmesan and basil, using more pasta water to thin out the sauce at any point if needed.

Season generously with salt and pepper to bring out the best in this simple sauce (work to taste), then serve up with more parmesan if desired and enjoy!