Wash and dry all produce. Preheat oven to 400 degrees. Bring a large pot of salted water to a boil. Thinly slice scallions, keeping greens and whites separate. Toss cauliflower on a baking sheet with a drizzle of olive oil and a pinch of salt and pepper. Roast until golden brown and tender, 20-25 minutes.

Boil the cavatappi: Add cavatappi to boiling water. Cook until al dente, 9-11 minutes. Drain.

Meanwhile, heat a large pan over medium-high heat. Add pancetta and scallion whites, and toss until crispy, 4-5 minutes. Remove from pan, retaining as much oil as possible.

Heat 1 TBSP butter in same pan over medium heat. Once melted, whisk in flour. Whisk constantly 1-2 minutes. Very slowly whisk in milk until combined. Add stock concentrate and simmer until thickened, 1-2 minutes. Remove pan from heat, then stir in cheese. Season with salt and pepper.

Stir cavatappi, pancetta mixture, and 3/4 of the cauliflower into cheese sauce. Transfer to a medium, lightly oiled baking dish. (TIP: If your pan is ovenproof, you can skip this step!) Top with remaining cauliflower, and cook until bubbling, 5-7 minutes.

Serve: Garnish with scallion greens and enjoy!