01 - Place peeled and cubed potatoes in a large pot, cover with cold water, add a pinch of salt, bring to a boil, then reduce heat and simmer for 15 to 18 minutes until fork tender.
02 - Drain the potatoes thoroughly. Add butter, warmed milk, heavy cream, salt, and pepper, then mash until smooth and creamy. Cover and keep warm.
03 - Pat steak cubes dry with paper towels, then season evenly with salt and black pepper.
04 - Heat olive oil in a large skillet over high heat. Add steak cubes in a single layer and sear for 1 to 2 minutes per side until browned but still juicy. Remove and set aside.
05 - Reduce heat to medium, add 2 tablespoons butter to the skillet. Once melted, add minced garlic and sauté for 30 seconds until fragrant.
06 - Return steak bites to the skillet, add remaining 2 tablespoons butter, and toss to coat thoroughly in garlic butter. Cook for 1 more minute. Remove from heat and sprinkle with chopped parsley.
07 - Plate steak bites over creamy mashed potatoes and spoon any remaining garlic butter from the skillet on top.