Preheat the oven to 350°F. Lightly spray a 13 x 9-inch baking dish or 3-quart baking dish with nonstick cooking spray and set aside.
Add the sliced beef sausage to a large Dutch oven or stockpot with ½ cup water. Cook over medium heat until the water evaporates and the sausage begins to brown. If needed, add more water ⅛ cup at a time.
Add the diced onions and cook for 3–4 minutes. Stir in the minced garlic and cook until the onions become translucent and fragrant.
Add the diced potatoes to the pot and stir to combine.
Pour in the chicken broth and heavy cream. Add ½ can of cheddar cheese soup, Slap Ya Mama seasoning, and black pepper. Stir well.
Cook over low heat just until the mixture begins to boil gently. Turn off the heat.
Stir in 1 cup of shredded sharp cheddar cheese until incorporated.
Carefully transfer the mixture to the prepared baking dish. Sprinkle additional cheddar cheese over the top if desired.
Cover tightly with foil and bake for 65–75 minutes, or until the potatoes are fork-tender.
Remove the foil and return the casserole to the oven for another 10 minutes, allowing the cheese on top to melt and lightly brown.
Let the casserole rest for a few minutes before serving.