Preheat oven to 425°.

Cut brussels sprouts in halves or quarters depending on how large they are.

Place them in a bowl or bag. Spray with oil, sprinkle with kosher salt and pepper and stir or shake the bag well.

Place them on a baking sheet lined with foil or parchment paper.  Bake for about 20 minutes or until tender.

While sprouts are roasting, heat a large nonstick pan on high. Add butter.

Add onions, stir for about 2 minutes, then reduce heat to low. Add garlic and continue cooking until onions are softened and starting to brown. I just let them cook for about 10-15 more minutes, stirring occasionally while the brussels sprouts are roasting but if you have an electric stove, you may want to move them off the burner when tender otherwise the heat will be too much and they may burn.

When sprouts are almost done, finish the sauce.  Add half and half and sherry to the onion mixture. Heat on medium stirring occasionally.

When sauce starts to thicken, add parmesan cheese, bacon crumbles and roasted brussels sprouts. Serve immediately, although these are great reheated as well.