Clean the chanterelles and peel the carrots. Place the chanterelles and crushed garlic in a bowl and add white wine vinaigrette and a small amount of thyme. Wrap the bowl with plastic wrap and place on top of a heated oven (400 degrees). Peel off the outer layers of the carrots so only the marrow remains; use the left overs for purée. Place leftover carrot pieces and heavy cream in a pot and boil until tender. Place the tender carrot pieces in a blender and add a small amount of the heavy cream that was used for boiling the carrots. Blend until smooth. Add salt and pepper to taste.
Peel the potatoes and cut them into 1 1/2 inch slices. Cut the slices potato with a circle cutter, 1 piece per slice of potato. Add the circle potatoes to a pan together with butter, water, and salt. Let the water evaporate from the pan so the potatoes will start frying in the butter until golden brown, and flip them over to fry on the other side as well. Meanwhile sear the meat and place in the oven for roughly 10 minutes; take out and leave to rest. Chop the rest of the thyme and add to the demi-glace; add butter while whisking so the sauce won't separate. Heat up a pan and sauté the carrots and chanterelles in butter and oil.
Plating: Place the carrot puree as a line on the bottom of the plate. Drag a spoon through it, then add the meat in the middle and place potato fondants next to the meat mixed roughly. Add the carrot marrows on top of the potatoes and place the chanterelles neatly on the carrots and potatoes. Serve the sauce on the side and serve. Bon appetit.