Cook the pasta according to the package directions.
Set aside 1/2 cup of pasta water before draining. Drain and do not rinse the pasta.
Warm the oil in a large skillet over medium-high heat.
Add the garlic. Saute for about 30 seconds until fragrant.
Add the mushrooms, asparagus, chili pepper flakes and 2 tablespoons of butter.
Stir to coat and continue stirring and cooking fora bout 3 minutes, until the mushrooms soften and the asparagus is bright green and slightly tender.
Add the parsley and cook for 1 minute.
Add the cooked pasta and sprinkle with 1/2 teaspoon salt, pepper and lemon juice. Toss to combine.
Add a splash of the reserved pasta water, about 1/4 cup, if pasta is dry.
Add an additional splash of the reserved water only if it is need.
Taste the mixture and add more salt only if needed. Stir in 1 tablespoon of butter and top with cheese.
Serve with lemon wedges if desired.