In a mixing bowl, melt 4 tablespoons of butter and stir in 1/4 cup of Irish whiskey. Immerse the sirloin steak in the marinade, ensuring it is well-coated. Let it marinate in the fridge for at least 3 hours, ideally up to 24 hours.

Preheat a cast iron skillet over medium-high heat. Remove the steak from the marinade and let the excess drip off. Sear the steak for 3-4 minutes on each side.

Transfer the steak to a preheated oven at 350°F and bake for approximately 10 minutes, or until reaching your desired doneness (130°F for medium-rare).

While the steak is baking, peel and chop 2-3 medium russet potatoes. Boil in a pot of salted water until tender, about 15-20 minutes. Drain and mash, then fold in 1 cup of cooked and chopped kale. Season with salt and pepper to taste.

In the same skillet, reduce heat and add 1 sliced shallot. Sauté for 2-3 minutes until translucent. Deglaze the pan with a splash of Irish whiskey and stir in 1 cup of heavy cream. Simmer until thickened.

Serve the dish with creamy colcannon on each plate, sliced steak on top, and drizzle the whiskey cream sauce over it. Enjoy while warm!