Melt the vegan butter in a large skillet over medium heat. Add the onions & a pinch of pepper and cook down for 3-5 minutes, or until tender - stirring frequently.
Add the oil & the tomatoes to the skillet and continue to cook down for 5-8 minutes, or until the tomatoes burst. Lower the heat as needed so the onions don't burn.
Add the garlic and cook for 60 seconds. Add the dry pasta & broth and bring to a boil. Lower the heat and simmer for 5-8 minutes, or until the pasta is cooked through and the broth has been absorbed (see notes).
Add the basil & gently toss one more time. Taste and add salt if needed. Serve right away with more fresh basil on top.
Video
Notes
You want to gently toss the pasta as it cooks. Capellini is super thin, so the more you mess with it, the more likely it is to break.
You can use a thicker pasta, like spaghetti or bucatini, but the cook time will be longer and you may need to add more broth.
Bulk this up with some plant protein! Add in a can of chickpeas or sauté some vegan sausage with the onions.