Wash and dry all produce. Bring a large pot of salted water to a boil. Trim, then thinly slice scallions, separating greens and whites. Cut any large broccoli florets into bite-sized pieces, then place in a large, microwave-safe bowl with a big splash of water. Cover with plastic wrap; poke a few holes in wrap.

Once water is boiling, add fusilli to pot. Cook, stirring occasionally, until al dente, 9-11 minutes. Scoop out and reserve 1/2 cup pasta cooking water, then drain thoroughly.

Add pancetta to a large pan and place over medium-high heat. Cook, stirring often, until almost crisp, 5-7 minutes. Add scallion whites and cook until softened, about 1 minute more. Remove both ingredients from pan with a slotted spoon, keeping as much oil in pan as possible.

Microwave broccoli in bowl on high heat until tender, about 5 minutes (microwaves vary). Drain thoroughly. Meanwhile, melt 2 TBSP butter in pan used for pancetta over medium heat. Add flour and stir constantly until it loses its raw smell, about 2 minutes. Slowly pour in milk, whisking to combine.

Stir stock concentrates and 1/4 cup pasta cooking water into pan. Let sauce simmer until thickened, 2-3 minutes. Remove pan from heat and stir in cream cheese and Italian cheese. Season with salt and pepper and set aside. Place fusilli, pancetta mixture, broccoli, and 1 TBSP butter in pot used to cook pasta. Add sauce, stirring to coat.

Return pot to low heat. Stir fusilli mixture until warmed through and butter melts, 1-2 minutes. (TIP: Add more pasta cooking water if sauce seems dry.) Season with salt and pepper. Divide between plates and sprinkle with Parmesan and reserved scallion greens.