Heat a large pan over medium-low heat. Add the olive oil and garlic and cook for 1 minute.
Add the broccoli and ¼ cup of the broth to the pan. Cover and cook for 4-6 minutes, or until the broccoli is just soft when poked with a fork. Remove the lid, add the spinach, and stir until wilted.
Transfer the vegetables to a blender with the remaining ¼ cup broth, the heavy cream, shredded cheddar cheese, and butter. Blend until smooth, adding a pinch of salt to taste if desired.
Meanwhile, cook the pasta according to package instructions until al dente; drain.
Toss the cooked, drained pasta with as much or as little sauce as you like and warm through if needed. Top with Parmesan and cracked black pepper or use mozzarella and olive 'eyeballs' for a Halloween garnish if desired.