Adjust rack to top position and preheat oven to 425 degrees. Bring 1 TBSP butter (1½ TBSP for 4 servings) to room temperature. Wash and dry produce.

Trim and quarter zucchini lengthwise; slice crosswise into ¼-inch-thick quarter-moons. Halve, peel, and dice half the onion (whole onion for 4) into ½-inch pieces.

In oven-ready tray, mix together zucchini, diced onion, shrimp, curry sauce base, crème fraîche, half the curry powder (all for 4 servings), salt, and pepper until thoroughly combined. (For 4, evenly divide ingredients between two trays.)

Bake shrimp curry on top rack (be sure your oven has preheated!) until zucchini and onion are tender, shrimp are cooked through, and curry has slightly thickened, 28-32 minutes, stirring every 10 minutes. (For 4 servings, bake two trays side by side on top rack.)

When curry has 3 minutes left, remove tray from oven; add peas and stir to combine. Return to top rack and bake until peas are warmed through, 1-2 minutes.

Toast pitas. Spread toasted pitas with softened butter, then cut each pita into quarters.

Divide shrimp curry between bowls. Serve with buttered pitas on the side.