In a medium skillet over medium-high heat, brown the ground beef along with the chopped onion until the meat is no longer pink and the onions are soft, about 5-7 minutes. Drain excess grease if necessary.
Transfer the meat and onion mixture to your slow cooker.
Add the tomato sauce, diced tomatoes, pinto beans, chili beans, taco seasoning, chili powder, garlic powder, cayenne pepper, and salt to the slow cooker. Stir well to combine all ingredients.
Cover and cook on low for 6-8 hours or on high for 4-5 hours.
Just before serving, stir in 1 cup of the shredded cheddar cheese until melted and well incorporated.
To serve, place a handful of Fritos in individual bowls, top with the cheesy chili, then sprinkle with remaining cheddar cheese and additional Fritos.
Add any optional toppings as desired and enjoy!