Place potatoes in a medium saucepan and cover with water. Add about a teaspoon of salt. Bring to a boil and simmer until just tender, but still a little firm.
Drain potatoes and place in a greased 2-quart baking dish.
Melt butter over medium heat in a medium saucepan. Sprinkle flour into pan. Stir and cook 1 minute.
Gradually whisk in the milk. Bring to a boil and simmer until thickened.
Stir in seasoned salt, pepper, and garlic powder.
Remove from heat. Add Velveeta and stir until melted. Pour sauce over potatoes.
Sprinkle cheddar cheese on top. Bake in a 350 degrees for 25 minutes.