Preheat the oven to 350°F. Rinse the potatoes thoroughly and then pat them dry. Put them on a baking sheet, drizzle with olive oil, and then sprinkle with salt. Roast the potatoes in the oven for 50 minutes, then allow them to cool a little before freezing them for 1 hour.
Slice the steak into chunks and fry the meat in olive oil. Add the onions, carrots, mushrooms, and garlic, and sauté everything for 10 minutes, stirring occasionally.
Toast the flour and tomato paste for a second and then season everything with salt and pepper. Deglaze the skillet with dark beer.
Now add the beef broth, bay leaves, and rosemary, then put the lid on the skillet and let the stew simmer for 45 minutes on low heat, stirring occasionally.
Grate the goat cheese over the beef stew.
Now grate the frozen potatoes over the stew and put the cottage pie in the oven for 25 minutes at 350°F. Garnish with chives before serving.
