Cut the broccoli into bite-sized pieces and blanch in boiling water.
Mince the garlic and slice the onion.
Heat olive oil in a pan and sauté the garlic and onion.
Add the broccoli and stir-fry together.
Pour in the tomato sauce and heavy cream, then bring to a simmer.
Season with salt and pepper.
Cook the spaghetti, add to the sauce, and mix well.
Transfer to a plate and finish with grated Parmesan cheese.