First, prepare your cashews by placing them into a bowl. Pour boiling water on top of them so that they are fully submerged. Let sit for 30 minutes.
Preheat the oven to 400ºF and line a baking sheet with tin foil.
Place tomatoes, onions, and garlic onto the baking sheet. Drizzle with 2 tablespoons olive oil and season with 1/2 teaspoon salt and 1/4 teaspoon ground pepper. Toss, making sure everything is coated.
Roast veggies at 400ºF for around 20 minutes.
While vegetables are roasting, prepare your pasta by following the direction on the back of the box. Make sure reserve 1 cup of starchy pasta water for later.
When the vegetables are done roasting, remove the baking sheet from the oven and carefully remove the skin from the tomatoes. The skins should come off pretty easily at this point. Then, roast for an additional 10 minutes.
Now it's time to make your creamy vegan pasta sauce. Strain the cashews from the water they were soaking in and then place them into a high-speed blender.
Transfer all ingredients from the baking sheet (including the juices) into the blender along with 2 tablespoons olive oil, 1/2 teaspoon salt, 1/2 cup of starchy pasta water, and 1/2 tablespoon lemon juice. Blend on high until smooth. Taste the pasta sauce and add more water as needed along with more salt.
Toss the cooked pasta with the sauce. If it's no longer hot, you can reheat on the stovetop.
Servewith fresh basil, cracked black pepper, red pepper flakes, and vegan parmesan.