Place potatoes in a pot of salted water. Bring to a boil and boil until just tender. Drain well and place in the prepared baking dish.
Heat a large nonstick skillet over medium-high heat. Add oil and sausage and cook until sausage is browned. Remove sausage from skillet and place in the prepared baking dish with potatoes.
Wipe skillet clean and add butter. Melt over medium heat. Add flour and cook and stir for 1 minute.
Gradually whisk in half-and-half. Bring to a simmer. Add garlic powder.
Turn heat to low and add velveeta. Stir until melted.
Add half the cheddar cheese and stir until melted. Remove from heat. Taste for seasoning and add salt and pepper to taste.
Pour cheese sauce over potatoes and sausage. Sprinkle the remaining cheese on top.
Bake in 350 degree oven for 25 to 30 minutes.
Notes
This dish can be enjoyed as a side or a main dish.