- 1 1/2 sticks (3/4 cup) unsalted butter, softened
- 1 lb medium shrimp in shell (31 to 35 per lb), peeled and deveined
- 1 teaspoon salt
- 1/2 teaspoon black pepper
- 1/4 cup minced onion
- 2 1/2 teaspoons fresh lemon juice
- 1/8 teaspoon cayenne
- 10 slices firm white sandwich bread, crusts discarded and each slice cut to form 4 triangles
- 3 tablespoons unsalted butter, melted
- Garnish: whole cooked shrimp
- Heat 2 tablespoons butter in a 10-inch heavy skillet over moderately high heat until foam subsides, then sauté shrimp with salt and black pepper, stirring, until just cooked through, 1 1/2 to 2 minutes. Transfer shrimp with a slotted spoon to a food processor, reserving skillet (do not clean).
- Cook onion in 1 tablespoon butter in skillet over moderately low heat, stirring occasionally, until softened, 2 to 3 minutes. Scrape onions into processor and cool mixture to room temperature, about 15 minutes. Add lemon juice, cayenne, and remaining 9 tablespoons butter and pulse until shrimp are finely chopped. Pack shrimp butter into a 2-cup ramekin or serving bowl and chill, its surface covered with plastic wrap, at least 6 hours (to allow flavors to develop). Bring to room temperature 45 minutes before serving.
- Put oven rack in upper third of oven and preheat oven to 400°F.
- Brush 1 side of bread triangles lightly with melted butter and toast, buttered sides up, in a large shallow baking pan until golden around edges, 6 to 8 minutes. Transfer to a rack to cool. Serve toast points with shrimp butter.