½cupdairy-free grated parmesan alternativefinely grated, plus more for serving
Freshly ground black pepper
Cook pasta in a large pot of boiling salted water, stirring occasionally, until very al dente, about 2 minutes less than package directions.
Heat 2 tablespoons of oil in a large pan over medium-high heat.
Add the sliced mushrooms in a single layer, and cook without stirring until edges are brown and starting to crisp. This takes about 3 minutes. Then stir the mushrooms and continue to cook, stirring occasionally for about 5 more minutes. When done, the edges will be brown and crispy, but be careful not to let them get too burnt. Note: you may need to do two batches of mushrooms in order to cook them in a single layer. Simply repeat this step with 2 more tablespoons of oil and remaining mushrooms if you need to do so.
Reduce heat to medium-low and, if you cooked mushrooms in two batches, return all of the mushrooms to the pot. Add garlic and onions and cook, stirring often, until garlic and onions are translucent and softened. This will take about 2 minutes.
Using tongs, transfer cooked pasta to the pan with mushrooms. Add coconut milk plus ½ cup of the hot starchy reserve pasta cooking liquid. Increase heat to medium, bring to a simmer, and cook until pasta is cooked through and liquid is slightly thickened, about 3 minutes. Be sure to toss the pasta regularly during this time.
Remove from heat. Add lemon zest and juice, parsley, butter, Parmesan alternative, pepper, and toss to combine. Taste and season with more salt if needed. Serve immediately and garnish with more parsley and Parmesan alternative, if desired.
Be sure to save some of the hot starchy pasta water to help create this dairy-free creamy sauce.