In a large pot, bring water to a boil. Add the cubed potatoes and cook until tender, about 15-20 minutes. Drain the potatoes and return them to the pot. Add milk, 1/4 cup butter, salt, and pepper. Mash until smooth and creamy. Set aside and keep warm.

In a skillet, heat 1 tablespoon of olive oil over medium heat. Add the sliced zucchini, garlic powder, salt, and pepper. Sauté for about 5-7 minutes until tender but still crisp. Remove from heat and set aside.

Season the tenderloin medallions with salt and pepper on both sides. In a large skillet, heat 1 tablespoon of olive oil and 1 tablespoon of butter over medium-high heat. Add the medallions and cook for about 3-4 minutes per side for medium-rare, or until desired doneness. Remove from the skillet and let rest.

In the same skillet used for the steak, melt 1 tablespoon of butter over medium heat. Add the chopped shallot and sauté until translucent, about 2 minutes. Pour in the beef broth and scrape any browned bits from the bottom of the skillet. Let it simmer for 2-3 minutes. Stir in the heavy cream and crushed peppercorns. Simmer until the sauce thickens slightly, about 3-4 minutes. Season with salt to taste.

Plate the mashed potatoes and top with sautéed zucchini. Place the steak medallions alongside and drizzle with the creamy peppercorn sauce. Enjoy!