Preheat oven to 400 degrees F.
Cut the potatoes, green pepper, red pepper, and onion into 3/4-inch pieces. Add to a large mixing bowl.
Pour the olive oil over the top of the vegetables and toss until they are coated.
Add the celery salt, salt, and pepper and toss to coat.
Spray a 12-inch cast-iron skillet with a non-stick cooking spray. Spread the vegetables in the skillet.
Place in the preheated oven Bake for 40 minutes or until vegetables are tender, stirring every 10 minutes.
Top the vegetables with the cheddar cheese and bacon pieces. Place back in the oven and bake for an additional 5 minutes or until the cheese is melted. Serve.