Start by bringing a large pot of salted water to a boil. Add your choice of pasta and cook according to package instructions until al dente. Drain the pasta, reserving about 1 cup of the pasta water for later. Set the pasta aside.
In a sauté pan over medium heat, melt 2 tablespoons of butter. Once melted, add the diced onion and sauté for about 3-4 minutes until it becomes translucent. Add minced garlic and cook for an additional minute until fragrant.
While the onion and garlic are cooking, place the drained roasted red peppers in a blender or food processor. Blend until smooth. If you prefer a chunkier sauce, you can pulse it a few times instead.
Add the blended roasted red peppers to the sauté pan with the onion and garlic. Pour in 1 cup of chicken stock or vegetable broth. Season with salt, pepper, and dried basil. Stir to combine and let it simmer for about 5 minutes so the flavors meld together.
Reduce the heat to low and stir in the heavy cream. Allow the sauce to heat through but do not let it boil. Add the grated Parmesan cheese gradually, stirring until melted and smooth. If the sauce is too thick, you can add a bit of the reserved pasta water to reach your desired consistency.
Add the cooked pasta to the sauce, tossing to coat evenly. Taste and adjust seasoning if necessary. If you want a creamier texture, add more heavy cream or pasta water.
Serve the pasta immediately, garnished with extra Parmesan cheese and a sprinkle of fresh basil if desired. Enjoy the flavors of this Seriously Amazing Roasted Red Pepper Pasta!