Penne with creamy broccoli and mushroom sauce

What to prepare on a Sunday when your decidedly not in the mood for leftovers? Since I had mushrooms and broccoli on hand, I prepared Penne with creamy broccoli and mushroom sauce. Here's what you'll need:

2 large onions, sliced
2 pints mushrooms, sliced
3 cups cut up broccoli florets and stems
2 to 3 tbsp olive oil
salt and pepper
1 pound dry Penne pasta
salted water to boil the pasta
sauce:
2 tbsp olive oil
2 tbsp flour
2 cups of milk or almond milk (for dairy free version)
1/8 tsp nutmeg
1/2 tsp garlic powder
salt and pepper
1/4 cup kosher grated Parmesan cheese (optional)

Start by bringing salted water to a boil in a large pot. Then in a large saute pan, add 2 tbsp olive oil and heat on high, then to that add the sliced onions which needs to be sauteed for 2 to 3 minutes, then add the broccoli and mushrooms and saute for a few more minutes till tender, add salt and pepper to taste and toss. Remove from pan and set aside for now, then in the same pan, add the remaining oil, then flour and whisk for 1 minute, then add the milk or liquid and whisk till it becomes thick and creamy. To the sauce add the remaining spices and check for seasoning, then add back to the pan the cooked vegetables, the cooked pasta, and about 2/3 of a cup of the boiling pasta water. Toss together, if adding Parmesan, add it in at this point and toss again. Serve with salad and enjoy!