Defrost spinach at room temperature. Clean and clean the mushrooms and carefully break out the stems. Heat 2 tablespoons of oil in a frying pan and fry the mushrooms for approx. 5 minutes, turning them over. Finely chop the mushroom stems. Peel onion and cut into cubes. Wash tomato and cut into cubes.
Heat 1 tbsp. oil in a frying pan and fry pine nuts, mushroom stems and onion for approx. 4 minutes, turning them over. Add spinach and tomato and season with salt and pepper. Cut cheese into cubes and fold in. Fill the mushrooms with the vegetable mixture and cook in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 15 minutes
Waiting time approx. 30 minutes