Cook sausage in a skillet on the stove breaking it up into crumbles as it cooks. Cook until it is no longer pink. Remove from the skillet and drain on paper towels on a plate.
Stovetop method
Add all the ingredients to a large skillet and stir. Cook on low stirring every few minutes until the cheeses are melted and hot. Serve.
Slow cooker
Add all the ingredients to a slow cooker and stir. Cook on low stirring every 20 to 30 minutes until the cheeses are melted and hot. Serve.
Oven method
Add all the ingredients to a large casserole dish and stir. Cover. Cook on 375℉ stirring every 20 to 30 minutes until the cheeses are melted and hot.
*For the oven method, after the dip is hot I like to add 1 to 2 cup(s) of shredded cheddar to the top. (This is in addition to the cheddar cheese that's in the dip.) So after it's hot and you stir it for the last time, sprinkle the shredded cheese over the top and cook until it melts. Serve.
Serve hot with Frito Scoops, tortilla chips, or a sturdy cracker.
Notes
I recommend using fresh onion and garlic it always provides better flavor in my opinion. However, if you don't have fresh on hand garlic powder and onion powder are fine to use. I recommend the first time you make this recipe use half of the seasonings that I have listed, taste, and add more if you prefer. Personally, I like a lot of seasoning.
I realize the substitutions for fresh onion and garlic aren't what is typically recommended for fresh onion and fresh garlic to onion powder and garlic powder however, for this recipe, these are the conversions I use. As always, adjust the seasonings to your tastes.