Make the filling Mix together ricotta, crabmeat, 1/2 tsp salt, 1/8 tsp pepper and red pepper flakes
Make the ravioli: Lightly flour a baking sheet. Working in batches arrange 45 wonton wrappers ona work surface. Keep remaining wrappers covered with a damp paper towel. Mound 1 tsp crab filloing in the center of each Brush edges of wrappers with egg wash and top each with another wrapper. Press edges to seal. Cut out circles using a 2 1/4 cookie cutter. Transfer to a baking sheet.
Bring a large pot of salted water to a boil. Working in 2 batches, cook ravioli until they rise to the top 2 to 3 minutes.
Meanwhile make the sauce: Heat a large skillet over medium heat. Melt 4 tbs butter and heat until just bubbling and frothy. Transfer first batch of ravioli to skillet using a slotted spoon along with about 2 tbs cooking liquid Add 1 tsp chopped lemon peel and 1 tsp juice and swirl to combine. Transfer to plates.
Repeat with second batch of ravioli. Carnish with chervil.