Bring a large pot of salted water up to a boil and drop your pasta. Cook the pasta just under al dente, you want it to be undercooked because you want it to finish cooking in the sauce. Save about 1 cup of the pasta water when you drain your noodles.
Meanwhile, on medium-high heat warm up enough olive oil in a large skillet to coat the bottom of the pan. Once the oil is hot, (test with a piece of mushroom to see if the oil is hot enough) sear off all of your mushrooms. You will need to do this in batches due to the volume of mushrooms. Let the mushrooms get a hard sear, do NOT mix around the mushrooms until you get really good color on one side. The other side will not develop as much color due to the amount of water released. Let the water cook off before you do the next batch of mushrooms. Take out the mushrooms and keep them in a bowl to the side.
Lower the heat to medium-low and melt 1/2 stick butter and add 1/4 c. of garlic paste and 2 tbsp. of red chili flake and add in your green onion whites. Mix for 3-4 minutes until the raw smell of garlic goes away.
Add in 2/3 c. of heavy whipping cream if you would like. (If you're making this recipe vegan I would melt 8 oz. of cream cheese now or in step 6, either way, is fine!)
Add in all of your cherry tomatoes and wait for them to burst, stir occasionally.
Add in your pasta and cut up your cream cheese into blocks and add to the pasta. As you stir it'll melt down and make your sauce super creamy!
Now add your spinach in batches. 1 pound looks like a ton but it will wilt down to nothing! I add it in a couple of handfuls at a time and I cover the pan for about 30 seconds and let the spinach wilt down and then I mix it in and add the next batch.
Add the juice of one lemon and mix it all together. Now garnish with lemon zest and the greens of your green onions. I also added parmesan cheese for garnish. I chose to serve with garlic crostinis and bruschetta!