Begin by bringing a large pot of salted water to a boil. Add spaghetti and cook according to package instructions until al dente. Reserve a cup of pasta water before draining.

In a large skillet, heat the olive oil over medium heat. Add the minced garlic and sliced mushrooms, sautéing until the mushrooms are golden and tender, about 5-7 minutes.

Toss in the chopped spinach and cook just until wilted, about 2-3 minutes.

Lower the heat and pour in the heavy cream, stirring to combine with the sautéed ingredients. Gradually add the Parmesan cheese, stirring until melted and creamy.

Add the drained pasta to the skillet, tossing to coat in the creamy sauce. If the sauce is too thick, gradually add a small amount of reserved pasta water until desired consistency is achieved.

Taste and adjust seasoning with salt, pepper, and optional red pepper flakes for some heat.

Enjoy immediately with extra Parmesan cheese if desired.