Start by boiling penne pasta according to package directions. Rinse the broccoli well and cut it into small florets.
While pasta is boiling, put a steamer tray right over the pot and steam broccoli florets, too. When it’s finished, you can begin the cheese sauce.
In a large pot add onion and garlic and cook with butter over medium heat until softened (about 2-3 minutes).
Reduce heat to med-low, add in flour. The flour and butter will form a paste like mixture (roux). Whisk continuously for a couple minutes.
Add soymilk and dry mustard. Increase heat to medium and heat for 5 minutes or until it thickens. When it is thick enough to coat the back of a spoon, it’s time to add the cheese.
Turn the burner off and whisk in the shredded cheese and parmesan until it is fully melted in.
Give the cheese sauce a taste and add salt and pepper to taste. Stir in cooked penne pasta and broccoli. Serve immediately.
