Preheat oven to 400 degrees.In a small bowl, mix together the parmesan cheese and paprika together. Set it aside. Next, cut the florets from the broccoli stem. Best to cut them into bite size pieces or large chunks. In a large pot filled with 8 cups of water, add 1 tsp. kosher salt, and 1 tsp. olive oil. The oil will help the pasta not stick to each other. Bring to boil and add the 16-ounce box pasta. Cook for 8 minutes or until al-dente. Then add the broccoli florets. Cook for an additional 4 minutes.
Drain the pasta and broccoli and set aside. Return the pot to the stove over medium low heat and begin making the roux. Add the butter. When melted, add the flour. Begin whisking immediately and slowly add the milk while whisking. Next, add in the heavy cream. Followed by salt, ground mustard, fresh ground black pepper (garlic powder and onion powder – optional).
Reduce the heat to low and continue whisking to mix the ingredients together. Add the cheddar cheese while whisking, when melted, add the mozzarella cheese. Continue whisking. The sauce will thicken and will become very cheesy. Turn off the heat. Add the pasta and broccoli. Mix well to combine. Then transfer to a baking dish. You can use a 9x13 baking dish.
Add one layer of the pasta mixture then spoon a few drops of the parmesan mixture. Alternate the layers until all the pasta is in the baking dish. Bake for 20 minutes or until golden brown on top. Serve warm as a side.