In a large cast iron skillet, lay the bacon in rows. Turn heat to medium and cook the bacon, flipping halfway through, about 10 minutes until crispy and brown. Remove the bacon from the pan onto paper towels, crumble and set aside. Drain most of the bacon drippings into a heat proof container leaving just a tad in the skillet to sauté the Brussels sprouts in.
Place the skillet back on the stove at medium-high. Add butter. Once melted add minced onion and Brussels sprouts.
Sauté, tossing occasionally until the sprouts are crisp, tender and golden brown. About 7 to 10 min. Add the crumbled bacon back to the pan and toss. Turn off heat.
In a small sauce pan over medium high heat add heavy cream, cheese, garlic salt and pepper.
Pour over the top of the roasted Brussels. Serve or top with optional bread crumbs, step below.
Optional: top with 1/4 cup panko bread crumbs and place under the broiler for 2 min until golden.