Crab Ravioli with Lemon Butter

INGREDIENTS

• For the filling:
• 1 cup ricotta cheese (8 ounces)
• 1 cup lump crabmeat, such as peekytoe (8 ounces)
• Coarse salt and freshly ground pepper
• 1/8 teaspoon red-pepper flakes
• For the ravioli:
• All-purpose flour, for baking sheet
• 90 wonton wrappers (two 12-ounce packages)
• 1 large egg, lightly beaten, for egg wash
• Coarse salt
• For the sauce:
• 1 stick unsalted butter
• 2 teaspoons lemon peel, very finely chopped, plus 2 teaspoons fresh lemon juice
• Garnish: fresh chervil