Soak beans in water 4 hours or overnight. Rinse beans and place in pot, cover with stock and water; add the halved onion and bay leaf. Bring to a boil, reduce heat a bit and simmer at a rapid bubble for 35-40 minutes until tender. Remove bay and onion, and pure half the beans and half their stock.
Heat a skillet over medium-high heat with EVOO, 4 turns of the pan. Add chopped pancetta and render 2-3 minutes then add the chopped onions, celery, carrots, rosemary, thyme, garlic, chili pepper and season with salt and pepper. Cook vegetables partially covered to soften, about 12-15 minutes, stirring occasionally.
Bring a pot of water to a boil for the pasta. When water is boiling, salt it, drop the pasta and cook to al dente.
While the pasta is working, stir in tomato paste to vegetables until fragrant, if using. Deglaze the pan with white wine. Add bean pure and whole beans with stock; stir to combine.
Reserve 1/2 cup starchy cooking water, add to sauce. Drain pasta and toss with sauce and parsley, cheese.
Serve in shallow bowls topped with a drizzle of EVOO. Pass more cheese at table.