- 8 ounces fresh morel mushrooms or 2 ounces dried morel mushrooms
- 8 tablespoons (1 stick) unsalted butter, room temperature, divided
- 3/4 cup chopped shallots, divided
- 1 garlic clove, minced
- 1 1/2 teaspoons chopped fresh thyme
- 6 4 1/2- to 5-ounce uncooked giant prawns or 24 large prawns
- Finely chop enough fresh morels or reconstituted morels to measure 1/2 cup (packed); reserve remaining morels. Melt 1 tablespoon butter in medium nonstick skillet over medium heat. Add 1/4 cup shallots and garlic; sauté 1 minute. Add chopped morels and thyme; sauté 2 minutes. If using dried morels, add reserved soaking liquid to skillet, leaving any sediment behind. Increase heat; boil until almost all liquid evaporates, about 8 minutes. Transfer morel mixture to small bowl; cool. Mix remaining 7 tablespoons butter into morel mixture. Season lightly with salt and pepper. (Morel butter can be prepared 1 day ahead. Cover and chill.)
- Using scissors, cut along back shell of each prawn all the way up to tail, exposing vein; pull out vein. Turn prawns over. Using small sharp knife and starting just below tail end, butterfly each prawn by cutting 1/4-inch-deep slit to opposite end. Place prawns, shell side down, on rimmed baking sheet. (Can be made 6 hours ahead. Cover; chill.)
- Preheat oven to 500°F. Melt 2 tablespoons morel butter in heavy large skillet over medium-high heat. Add remaining 1/2 cup shallots; sauté until golden, about 3 minutes. Add remaining whole fresh morels or reconstituted morels and sauté until tender, about 4 minutes.
- Meanwhile, spread 1 teaspoon morel butter over each giant prawn (or 1/4 teaspoon over each of 24 large prawns). Roast just until prawns are opaque in center, about 7 minutes for giant prawns or 4 minutes for large prawns. Top prawns with remaining morel butter, dividing equally. Return to oven just long enough to melt butter slightly, about 10 seconds.
- Transfer prawns to plates. Serve sautéed morels alongside.
- If using dried morels: Bring 3 cups water to boil in medium saucepan. Add dried morels. Remove from heat. Cover; let steep 1 hour. Using slotted spoon, transfer morels to bowl. Reserve soaking liquid.