Trim just the very bottoms off the Brussels sprouts and leave them whole. You can halve them if yours are a little bigger. Saute them in the butter and olive oil for about 10 minutes over medium heat. Don't let them get too brown. They should be al dente. Cook your pasta to an al dente stage. Add the cream to the sprouts and heat to simmering. Simmer for a few minutes to let the cream reduce a bit and finish cooking the sprouts. You want to sprouts to retain some of their bite. Add the lemon and zest to the cream and season with salt and pepper to taste. Slowly sprinkle in the cheese while stirring to melt and incorporate the cheese. Add in the cooked pasta and stir to combine. If the sauce is too thick, add some pasta water. If it is still very thin, add some more cheese. Serve with a garnish of parsley and lemon zest.