Wash the Jerusalem artichokes and cut into equal pieces. Place the Jerusalem artichokes in a large baking tray with 5 cloves of garlic and the rosemary/thyme. Sprinkle with a little olive oil, salt and pepper and bake for 45 minutes until golden brown.
Meanwhile, chop the shallots and thinly slice the mushrooms and sauté in a frying pan until golden brown. Chop the remaining garlic clove and add to the mushrooms.
After 2 minutes, add the cream and reduce to a nice sauce. Season to taste with salt and pepper.
Heat a frying pan, add a generous knob of butter with a sprig of thyme and fry the steak to your liking.