Heat a skillet over medium heat. Add the ground beef, chopped onion, and minced garlic. Cook, breaking the meat up, until the beef is browned and the onion is softened, about 6 to 8 minutes. Drain excess fat.

Spread the diced potatoes in an even layer across the bottom of the slow cooker. Distribute them so they cook evenly.

Spoon the cooked beef and onion mixture over the potatoes in a single layer.

Scatter the drained black beans and kidney beans across the beef. Try to distribute them so each serving gets beans.

Pour the can of cream of mushroom soup over the layered ingredients. Stir in or pour the cup of beef broth or water around the edges so the mixture steams and melds while cooking.

Sprinkle the chili powder, cumin, salt, and pepper evenly over the top. Gently push the seasonings into the surface.

Cover and cook on low for 6 to 8 hours or on high for 3 to 4 hours, until the potatoes are tender when pierced with a fork.

Five minutes before serving, sprinkle the shredded cheese across the top and replace the lid so it melts into a gooey layer.

Serve warm straight from the slow cooker.