Potato, Onion and Carrot Bake

My mom used to make something similar to this. I think it's easy and good.

5 or 6 Potatoes ( I like Idaho)
about 10 baby carrots
1 medium onion , sliced or diced
1 small red onion ( adds color)
1/2 of butter or margarine
Garlic Salt ( I like the "grinders"....roasted garlic sea salt
pepper to taste

Sliced potatoes (I use my Pampered Chef apple/peeler/corer/slicer to do mine... Gives it some "curly Q" effects.) I take the "core" since it's still all potato and slice it in the dish. I dice 10 baby carrots, both types of onion and toss it around. I top with about 1/2 cup butter or margarine and grind the sea salts and pepper over the dish. I toss it around. Preheat oven to 400 degrees and bake about 50 minutes until potatoes, carrots, and onion are cooked. Enjoy!