Preheat the oven to 425°F (220°C).
Wash and peel the potatoes, then cut them into bite-sized cubes.
In a mixing bowl, toss the potato cubes with olive oil, garlic powder, onion powder, paprika, chili powder, salt, and pepper until evenly coated.
Spread the seasoned potatoes on a baking sheet in a single layer.
Bake in the preheated oven for 25-30 minutes, or until the potatoes are crispy and golden brown, shaking the baking sheet halfway through for even cooking.
While the potatoes are baking, melt 1 tablespoon of butter in a pot over medium heat. Add 1 tablespoon of flour and whisk to form a roux.
Gradually whisk in 1 cup of milk, and continue stirring until the sauce thickens. Remove from heat and stir in the shredded cheddar cheese until melted and smooth.
Once the potatoes are done baking, remove them from the oven and drizzle the cheese sauce over the top.
Serve warm, garnished with a dollop of sour cream, chopped green onions, and sliced jalapeños if desired.