Preheat oven to 385°F,

Add the potatoes in a large pot and cover them with water. Boil the potatoes until a fork goes through them easily.

Drain the potatoes and transfer back to the pot.

Add the ¼ cup butter and sour cream.

Mash the potatoes. Season with salt and pepper.

Set aside while you prepare the onions.

Add the oil to a medium size skillet and allow it to heat.

Add the chopped onions and garlic. Cook the onions for a few minutes until translucent.

Then add ½ the bacon crumbles and allow them heat through and combine with the onions.

Add the mixture to the mashed potatoes and mix all together.

Transfer the potato mixture to 2 quart sized casserole baking dish that's been sprayed lightly with non-stick baking spray.

Cover the potatoes with the shredded cheddar cheese.

Sprinkle the remaining bacon crumbles over the top.

Bake in the oven for 10 minutes or until the cheese is melted and the casserole is heated through.

Garnish with the sliced green onions and enjoy.