This was delicious! I pseudo-carmelized the onions, which made the sauce sweet + umami.
1.5 cups of pasta water was a bit too much, I should have just added a little at a time. My sauce was runny, so I tried to thicken it up with a handful of cannned beans, about 0.25C riced cauliflower, and a bit of frozen pumpkin puree I found in my freezer. It was thicker but still tasted great and you didn't really notice all the veggies. A bit bland by then though, so I added more salt, lemon juice, onion and garlic powder, and black pepper