In a large bowl, combine mushrooms, olive oil, vinegar, red onion, garlic, oregano, diced sun-dried tomatoes, rosa tomatoes, chilly sauce, and thyme. Season with salt and pepper, to taste.
Transfer to an airtight container and place in the refrigerator for at least 1 hour.
Place a large frying pan on high heat. Add the gills of the mushroom up to a frying pan, cover with a lid or baking paper. Simmer for 10 minutes.
Turn the mushrooms over, add the marinade and give them another 5 – 10 minutes before serving.
Place cauliflower in a steamer over a large pot of boiling water. Steam for 15 minutes until tender.
In the same pot, heat the butter over medium-high heat.
Blend cauliflower and garlic in a food processor on a high setting until smooth.
Transfer blended cauliflower into the pot with the garlic.
Slice the mushrooms, arrange the spinach, garnish with the mashed cauliflower, and sprinkled with cheese and thyme.