Heat a large skillet over medium-high heat.
Add 1 tablespoon of butter to the skillet until melted.
Season the steak cubes with salt and pepper, then add to the skillet in a single layer.
Sear the steak bites for 2-3 minutes on each side until browned.
Remove the steak bites from the skillet and set aside.
In the same skillet, add the remaining butter and sliced mushrooms.
Sauté the mushrooms for about 4-5 minutes until golden brown and tender.
Add minced garlic and cook for an additional minute until fragrant.
Return the steak bites to the skillet and toss to combine.
Garnish with fresh parsley and serve immediately.