Cut Steak into 1x1 inch cubes, season, sear a minute on all sides, and baste with butter
In the same pan you used for the steak use the butter to sauté the shallots and garlic until fragrant. Then add in all the ingredients above whisking as you go.
Add Potatoes and Garlic in a Pot with salt and boil for 15-20 minutes or until fork tender. Mash the potatoes adding in milk, garlic, salt, and pepper. Serve with butter