01 - Place potatoes in a large pot, cover with cold water, add a pinch of salt, bring to boil, then reduce heat and simmer 15–18 minutes until tender.
02 - Drain potatoes thoroughly. Add butter, warmed milk, heavy cream, salt, and pepper. Mash until smooth and creamy. Cover and keep warm.
03 - Pat steak cubes dry with paper towels. 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 1–2 minutes per side until browned but still juicy. Remove from skillet and set aside.
05 - Reduce heat to medium. Add 2 tbsp butter to the skillet. When melted, add minced garlic and sauté 30 seconds until fragrant.
06 - Return steak to skillet, add remaining 2 tbsp butter, toss to coat in garlic butter, cook 1 minute, then remove from heat and sprinkle with parsley.
07 - Plate steak bites atop the mashed potatoes and spoon any remaining garlic butter from skillet over the top.