Dice the bell pepper and onion into 1-inch cubes. Slice the mushrooms. Set the veggies aside.
Preheat a deep skillet with butter over medium heat. Add the mushrooms and cook them until they soften.
Add the bell peppers and onions to the skillet and cook them until they soften.
Cook the pasta in a boiling pot of hot water for about 4 minutes less than the box instructions. Add the partially cooked pasta into the skillet with the veggies.
Add the heavy whipping cream, pressed garlic, and broccoli to the skillet. Cook for about 5 minutes.
Fold in the parmesan cheese and stir until evenly combined.