Wash and dry all produce. Adjust rack to upper position and preheat oven to 425 degrees. Quarter tomatoes lengthwise through stem ends. Trim and thinly slice scallions, keeping greens and whites separate. Zest lemon until you have 2 tsp zest, then cut into wedges.

Put panko and 1 tsp Tuscan heat spice (we’ll use more later) in a large pan. Season with salt and pepper. Place pan over high heat. Toast panko, tossing frequently, until golden brown and crisp, 3-5 minutes. Remove from pan and transfer to a plate. Wipe out pan.

Toss tomatoes with a drizzle of oil on a baking sheet. Season with salt, pepper, and 1 tsp Tuscan heat spice (save the rest for step 5). Roast in oven until softened, 15-20 minutes.

Heat a drizzle of oil in pan used for panko over medium-high heat. Add orzo and toss until lightly toasted, 2-4 minutes. Add enough salted water to cover generously and bring to a boil. Let boil, stirring occasionally, until orzo is al dente, 9-11 minutes. Scoop out and reserve 1 cup pasta cooking water, then drain orzo. Wipe out pan. Rinse shrimp and pat dry with a paper towel (you can do this while orzo cooks).

Heat a drizzle of oil and 1 TBSP butter in same pan over medium-high heat. Season shrimp with salt, pepper, and remaining Tuscan heat spice. Add to pan along with scallion whites. Cook, tossing occasionally, until shrimp are pink and firm and scallions have softened, 3-4 minutes. Stir in orzo, 1/2 cup reserved pasta cooking water, stock concentrate, 1 TBSP butter, and a squeeze or two of lemon juice (to taste).

Cook orzo mixture in pan, stirring, until liquids have reduced slightly, 1-2 minutes. (TIP: Add more pasta water if needed to loosen.) Stir in lemon zest. Season with salt and pepper. Divide between plates and top with tomatoes. Sprinkle with panko and scallion greens. Serve with any remaining lemon wedges on the side for squeezing over.