Place all ingredients in food processor and add a pinch of salt and pepper.

Blend until fully blended and incorporated and season to taste with salt and pepper.

Add potatoes to large pot of salted water, covering potatoes with water by at least one inch, and bring to a boil.

Once water comes to a boil, cover with lid and cook potatoes for about 15 to 18 minutes, until fork-tender.

While potatoes are boiling, in a separate medium-sized saucepan on medium heat, add olive oil and lightly sauté garlic until fragrant; about 30 seconds.

Add heavy cream, butter, kosher salt, and white pepper, whisk all contents together, and bring to a boil; reduce to low heat and simmer for 3 minutes.

Once potatoes are cooked, remove from water, place in a large bowl, and mash until most lumps are gone.

Add cheese, sour cream, hot cream mixture, and chives – in that order – and fold all ingredients together until well incorporated. Note: If cheese doesn’t melt, place bowl over a pot of boiling water and stir until cheese has melted.

Cover bowl with plastic wrap to keep mashed potatoes warm.

Thaw leg of lamb in refrigerator for 24 to 26 hours.

Take leg of lamb out of refrigerator and remove butcher’s twine.

Pat leg of lamb dry with paper towel, rub with 3 tablespoons grapeseed oil, and season generously with Omaha Steaks Seasoning on all sides; allow leg of lamb to come to room temperature on counter for an hour.

Preheat oven to 250 degrees Fahrenheit.

In a large cast-iron pan, add remaining grapeseed oil and bring to medium-high heat.

Sear leg of lamb in cast-iron pan on all sides to get a nice, browned crust; about 1 and a half to 2 minutes on each side.

Place seared leg of lamb on roasting rack, put roasting rack in oven, and cook for 1 hour and 15 minutes to 1 hour and 30 minutes, until internal temperature of 125 degrees Fahrenheit for medium-rare doneness. Remove from oven and let lamb rest for 15 minutes before slicing (carry-over cooking will raise internal temperature 5 to 10 degrees while resting). Cook longer for more desired doneness.