Heat a saute pan over medium heat. Add butter. When melted, crumble ground beef, onion, and bell pepper to pan. Allow to brown, undisturbed, until you see brown, crisp edges on the ground beef. Flip over and redistribute, allowing the other side to brown.
Season with salt, pepper, and garlic powder. Add worcestershire sauce, beef broth, water, and pasta to pan. Stir to combine.
Bring to a boil, cover, and reduce heat to low. Simmer for 11 minutes (or to "al dente" according to your pasta's package directions).
Remove lid. Most of liquid should be absorbed. Add heavy cream and shredded cheese to pan. Stir until cheese has melted. Remove from heat and allow to set for five minutes for sauce to thicken.
*Cheese should be freshly grated. Bagged, pre-shredded cheese is coated in a powder to prevent clumping, which can cause your sauce to be grainy.