In a large skillet, over medium heat, cook the hot dogs for 2-3 minutes or until heated through. Remove and set aside. Add the onions to the skillet and cook 2-3 minutes or until they start to soften.
Slice the hot dogs into ½ inch pieces. Preheat oven to 425F.
Pour the baked beans, bbq sauce, and yellow mustard into a 9x13 casserole dish. Stir to combine the ingredients.
Sprinkle in the sliced hot dogs and cooked onions. Stir to combine with the beans.
Top with tater tots. Sprinkle it with the shredded cheese.
Bake for 30 minutes or until the casserole is bubbly and the tots are golden brown and the cheese is melted.
Remove from the oven and enjoy!