Start by peeling out the papery skin from the garlic bulb but remember not two separate or peel the cloves.
Preheat the oven to 425 degrees.
Remove the top of the garlic bulb so that each clove gets separated and hence apply one teaspoon of oil to each clove. Cover with foil and bake foil 30 to 35 minutes until soft.
In a large vessel, heat the remaining oil on low heat and add chopped onions and let it cook for 15 to 20 minutes with occasional stirring until onion turns to be golden brown. Remove the content and blend them in a food processor until smooth.
Place the potatoes in a large saucepan and cover with water. Let it boil. After boiling, leave it uncovered for 15 to 20 minutes.
Discard the water and add butter, sour cream, cheese, milk, salt, pepper and onion to two potatoes with softened garlic. Mash until you obtain a smooth mixture.
Transfer the Mashed potato mixture in a container and let it freeze overnight. Cover the mixture and place it in the microwave at high temperature, with two times stirring and adding a little milk if required.
There you go with your delicious Texas Roadhouse mashed potatoes!