heat the olive oil in a large skillet or use the pasta pot. Once the oil is hot add the garlic, careful not to burn; for a few seconds then add the sprouts. Season well with salt and pepper and saute for 2-3 minutes. You want the sprouts still green and slightly wilted.
Add the lemon zest, stir to blend. Add 2 tablespoons butter and stir till melted. Sprinkle the flour in the stir until you no longer see it. Add the broth the stirring constantly until all the broth is added. simmer the sauce for 2-3 minutes.
Remove from the heat and stir in the lemon juice and the cooked pasta. Stir to blended; add most of the cheese; you want some for the top, taste and adjust the salt and pepper.
pre-heat oven to 400' F and cooking spray or butter a 2 quart baking dish, Add the mixture to the dish and sprinkle with the remaining cheese. Bake for 20-25 minutes, until the top is browned.