Season the steaks with salt and pepper on both sides.
Heat olive oil in a large skillet over medium-high heat.
Add the steaks and cook for about 4-5 minutes on each side for medium-rare, or until desired doneness.
Remove the steaks from the skillet and let them rest.
In the same skillet, reduce heat to medium and add heavy cream, whiskey, Dijon mustard, and Worcestershire sauce.
Stir well, scraping up any browned bits from the bottom of the pan.
Simmer for about 5 minutes until the sauce thickens slightly.
Stir in chopped parsley and remove from heat.
For the colcannon, boil the diced potatoes in salted water until tender, about 15 minutes.
In the last 5 minutes of cooking, add the chopped cabbage.
Drain the potatoes and cabbage, then return to the pot.
Add milk, butter, salt, and pepper.
Mash until smooth and creamy.
Stir in chopped green onions.
To serve, place a generous scoop of colcannon on each plate, top with a steak, and drizzle with whiskey cream sauce.