Shrimp Saltimbocca with Polenta

Position rack in center of oven; preheat broiler. Coat a baking sheet with cooking spray.

Place polenta rounds and prosciutto on the baking sheet. Broil on the center rack until the prosciutto is crisp, 4 to 5 minutes. Transfer the prosciutto to a plate. Continue broiling the polenta, turning once, until golden brown, about 10 to 12 minutes per side.

Meanwhile, whisk lemon juice and cornstarch in a small bowl. Sprinkle shrimp with 1/8 teaspoon pepper. Heat oil in a large nonstick skillet over medium heat. Add onion and cook, stirring, until beginning to brown, 2 to 3 minutes. Add shrimp and cook, stirring, until the shrimp just turn pink but aren’t cooked through, about 2 minutes. Pour in clam juice (or broth), bring to a boil and cook until the liquid is slightly reduced, about 2 minutes more.

Whisk the cornstarch mixture again and add to the pan along with sage and the remaining 1/8 teaspoon pepper. Cook, stirring, until thickened, 1 to 2 minutes. Top the polenta with the shrimp and sauce, crumble the prosciutto over the top and serve immediately.