First, leave the potatoes out to thaw. They will not cook correctly if you add them in the crockpot frozen.
Now, cook the ground beef on the stove. Once browned add into the crockpot.
In a bowl, mix the cream of mushroom and the milk using a whisk to get rid of any lumps. Then, pour it into the crockpot.
Add the thawed potatoes into the crockpot then mix everything together. Place the crockpot on high for 4 hours.
At the 4-hour mark add in half the cheese and mix it into the casserole. Then top the casserole with the rest of the cheese and add the lid on to help it melt quicker.
Carefully serve the casserole because the contents will be extremely hot.