Preheat oven to 350f degrees. In a large bowl, combine ranch dressing, taco seasoning and half the shredded cheddar cheese. Set aside.
Cut little potatoes in half (or quarter them if they are a bit larger.)
Add potatoes to bowl with ranch/taco seasoning an stir well until all the potatoes are coated.
Spread potatoes into a 2-quart baking dish (or an 8x8 square baking dish.)
Cover with aluminum foil
Bake for 45 minutes.
Remove foil and stir potatoes well. Return to the oven (uncovered) for another 15 minutes. Remove potatoes and sprinkle with the rest of the shredded cheddar cheese and bacon. The heat from the potatoes should melt the cheese. Or you can stick it under the broiler for a few seconds to melt quickly.