Begin by bringing a large pot of salted water to a rolling boil over high heat. Once boiling, add your spaghetti and cook according to package instructions, typically around 8-10 minutes until al dente. Reserve a cup of pasta water; then, drain the spaghetti and set it aside in a colander to keep warm.

In a large skillet, heat 1 tablespoon of high-quality olive oil over medium-high heat. Add the sliced button and oyster mushrooms to the pan, spreading them out evenly to ensure even cooking. Sauté for about 5-7 minutes until golden brown.

Lower the heat to medium and add another tablespoon of olive oil to the pan with the sautéed mushrooms. Toss in finely chopped garlic and cook for 1-2 minutes until fragrant.

Sprinkle in the chili flakes, and pour the reserved pasta water into the pan, adding about half a teaspoon of salt. Increase the heat and let the mixture reduce and emulsify for 2-3 minutes.

Toss the drained spaghetti into the skillet with the mushroom-garlic sauce, ensuring every strand is coated. Add in freshly chopped parsley and stir for about 1-2 minutes.

Transfer Mushroom Spaghetti Aglio Olio to serving plates. Top with grated Parmesan cheese and serve warm.