Wash the meat, pat dry and cut into fine strips. Peel, quarter and chop the onion. Peel and crush garlic. Mix prepared ingredients with gyros spice, oil, bay leaf and thyme. Cover and marinate for about 12 hours
Heat the fat. Sweat flour in it. Deglaze with milk and 1/2 l water while stirring. Bring to the boil and stir in the stock. Let simmer for about 5 minutes. Season to taste with salt and pepper
Clean, wash and slice the mushrooms. Drain the gyros, collect the seasoning oil. Heat 1 tbsp. seasoning oil. Fry the mushrooms in it. Season and take out. Fry the gyros in the frying fat for 3-4 minutes while turning.
Wash and slice the tomatoes. Dice cheese. Put some sauce in a greased casserole dish (approx. 16 x 26 cm). Place 3-4 lasagne plates on top. Layer gyros, tomatoes, mushrooms and the remaining lasagne plates alternately with the sauce. Finish with pasta plates and sauce. Spread cheese on top
Wash and pluck the thyme and sprinkle it on the lasagne. Bake in the preheated oven (electric cooker: 200 °C / convection oven: 175 °C/ gas: level 3) for approx. 45 minutes until golden brown