Char green tomatillos on a pan on medium high heat, turning occasionally
for 5 minutes, add onion, garlic and chili, continue cooking for 5 more minutes until ingredients are lightly charred. Remove from heat, add cilantro and pulse for 10 seconds on a food processor (or until you obtain a chunky texture). Season with salt to taste and reserve.
Heat the oil and sauté the onions until translucent, add the garlic and cook
for 2 more minutes. Incorporate the white and crimini mushrooms, sauté on medium high heat until lightly browned, add cilantro, mix and remove from heat
Place the cheese on a cazuela (earthenware) pot. Heat until cheese is completely melted and bubbly, add, sautéed mushrooms on top of the melted cheese (in the middle).
Serve with warmed flour tortillas and roasted green salsa. Enjoy