1. Start by preparing the potatoes. Bring a large pot of salted water to a boil. Add the peeled and quartered potatoes and cook until tender, about 20 minutes.
2. While the potatoes are cooking, heat olive oil in a large skillet over medium-high heat. Season the steak medallions with salt and freshly ground black pepper.
3. Add the medallions to the skillet and sear for about 3-4 minutes on each side, until browned and cooked to your desired level of doneness.
4. Add the minced garlic and a tablespoon of butter to the skillet. Swirl the garlic and butter around the medallions for about 1 minute to infuse flavor. Remove the steak from the skillet and let it rest.
5. Once the potatoes are done, drain them and return them to the pot. Add the heavy cream and unsalted butter. Mash until smooth and creamy. Season with salt and pepper to taste.
6. Serve the steak medallions over the mashed potatoes. Drizzle with the garlic-infused butter from the skillet and garnish with chopped fresh parsley if desired.

Pro Tip: If you want to add a bit of zest, sprinkle some lemon juice over the steak medallions before serving. It was a trick I picked up from my travels that adds a delightful brightness to the dish.