1In medium bowl, beat all crepe ingredients with wire whisk or hand beater until smooth. For each crepe, lightly butter 7- or 8-inch skillet; heat over medium heat until bubbly. Pour slightly less than 1/4 cup batter into skillet; rotate skillet until batter covers bottom. Cook until light brown; turn and cook other side until light brown. Stack crepes, placing waxed paper between each. Keep crepes covered to prevent them from drying out.
2In 2-quart saucepan, melt butter over medium heat. Cook mushrooms and 2 tablespoons of the onions in butter, stirring occasionally, until onions are tender. Stir in shrimp, crabmeat, half-and-half and cream cheese. Cook over medium heat, stirring constantly, until cheese is melted.
3Spoon about 1/4 cup seafood mixture down center of each crepe; roll up. Place in 11x7-inch (2-quart) glass baking dish. Sprinkle with Swiss cheese.
4Microwave uncovered on High 4 to 6 minutes or until cheese is melted and crepes are heated through. Sprinkle with remaining 2 tablespoons onions.