In a large pot or Dutch Oven if you have one, melt the butter (medium/medium-high heat) and add the ground beef. Cook until browned, breaking it up well as you cook it. Season this with the Salt, Pepper, and Garlic Powder while cooking.
Add the onion to the beef and continue to cook another couple minutes until the onion is softened well.
Dump in the broth and pasta, stir it all together well. Bring it to a simmer, cover it, and let it cook until the pasta is done. Stir this a couple times while cooking, this will take about 12 minutes.
Turn off the heat and pour in the cream, cheddar, and parmesan cheeses, mixing thoroughly. Cover and let sit a minute or two for the cheeses to fully melt and incorporate.