Bring a large pot of salted water to a rolling boil and cook pasta until al dente.
Reserve 1/2 cup of starchy pasta water, then drain the pasta.
Place a large skillet over medium heat and melt 2 tablespoons of butter.
Add the sliced mushrooms to the skillet and sauté undisturbed until browned.
Stir in the minced garlic and Aleppo pepper flakes, cooking until fragrant.
Deglaze the pan with the vinegar or white grape juice, scraping up any browned bits.
Add the spinach to the skillet and cook until just wilted.
Add the cooked pasta and the remaining tablespoon of butter to the skillet.
Toss everything together, adding the reserved pasta water as needed to create a glossy sauce.
Season with salt and black pepper to taste.
Serve immediately topped with freshly grated Asiago cheese.