In a large skillet, warm up 1 tablespoon of olive oil over medium heat. Once it's shimmering, add your mushrooms!

Add the sliced mushrooms and sauté for about 3–4 minutes, until they begin to soften and release their earthy aroma.

Toss in the chopped spinach, minced garlic, onion powder, salt, and pepper. Cook until the spinach wilts and the mushrooms are tender, about 2–3 minutes. Remove from heat and let cool slightly.

Lay out two large flour tortillas. Evenly distribute the mushroom and spinach mixture over each tortilla.

Sprinkle 1 cup of shredded cheese generously over the filling. Place the remaining tortillas on top.

In the same skillet, add more olive oil if needed and heat over medium. Place one quesadilla in the skillet and cook for about 3–4 minutes until golden brown and the cheese begins to melt.

Carefully flip the quesadilla and cook for another 3–4 minutes until crispy and golden. Remove and repeat with the second quesadilla.

Slice the quesadillas into wedges and serve warm with sour cream, salsa, or guacamole.