Makes 4 servings.

Preheat oven to 350°. Oil large rimmed baking sheet. Combine breadcrumbs, ½ cup hazelnuts and 2 tablespoons parsley in medium bowl. Open trout and sprinkle flesh side with salt and pepper. Press hazelnut mixture into flesh side of butterflied fish. Heat 1 tablespoon oil in heavy large nonstick skillet over high heat. Add 1 whole trout, hazelnut side down. Saute until golden, about 2 minutes. Transfer trout, hazelnut side up, to prepared baking sheet. Repeat with remaining olive oil and trout. Transfer trout to oven and roast until opaque in center, about 5 minutes.

Meanwhile, melt butter in same skillet over medium heat and allow to brown. Add 3 tablespoons crushed hazelnuts, 6 tablespoons parsley, lemon juice, and 1 teaspoon lemon peel; stir to combine. Season sauce with salt and pepper; pour over fish. Sprinkle with remaining 1 teaspoon lemon peel and serve immediately.