Place the whole red bell peppers on a baking sheet and roast in the oven for about 25-30 minutes or until charred, turning occasionally to ensure even roasting. Once done, remove from the oven and let them cool before peeling off the skin and removing the seeds.
In a large pot, bring salted water to a boil and cook the pasta according to package instructions until al dente. Reserve 1 cup of pasta water, then drain and set pasta aside.
In a skillet, heat olive oil over medium heat. Add the chopped onion and sauté until translucent, about 5 minutes. Add the minced garlic and smoked paprika, cooking for an additional 1-2 minutes until fragrant.
In a blender, combine the roasted red peppers, sautéed onions, garlic, coconut milk, nutritional yeast, salt, and pepper. Blend until smooth and creamy.
Pour the creamy sauce into the skillet with the sautéed onion and garlic, and heat on low for a few minutes. If the sauce is too thick, gradually add some reserved pasta water until the desired consistency is reached.
Toss the cooked pasta into the creamy sauce, making sure the pasta is well coated. Heat for another minute or so to warm through.
Serve immediately, garnished with fresh basil leaves and a sprinkle of crushed red pepper flakes, if desired.