Wash and clean the soft-shell crabs. Blend the salt and pepper into the flour and coat the crabs lightly. Dip the crabs into the egg-and-milk mixture, then dredge through the seasoned flour. Shake off excess flour.
Melt butter in skillet and add green onions and mushrooms. Saute until the onions just begin to soften.
Add crabmeat, garlic, and wine. Bring the wine to a boil and let most of it evaporate. Agitate but don't stir the pan, to keep from breaking up the crabmeat.
Add the cream, salt, and pepper. Allow to reduce over medium-high heat for one to two minutes, until the sauce is noticeably thicker.
Add cooked fettuccine and toss with sauce. Remove from heat.
Heat about an inch of vegetable oil in a deep skillet or saucepan to 375 degrees. Drop crabs in oil two at a time and fry until golden brown. Drain excess oil in a fine sieve.
Divide the pasta among plates and top with fried soft shell crab.