Bring large pot of water to boil. Cook elbow pasta according to package directions until al dente. Drain and set aside.
Meanwhile, combine half and half and milk in saucepan over medium heat. Warm through, being careful not to let it come to boil.
In another large saucepan, melt butter over medium heat. Whisk in flour and cook 1 minute. Slowly whisk in hot milk and cook until thickened, about 5 minutes. Stir in Grand Cru and mozzarella. Season to taste with salt and pepper and add dry mustard. Add cooked macaroni to cheese sauce and stir to combine. Pour macaroni and cheese into shallow dish to cool, or refrigerate overnight.
When macaroni and cheese has completely cooled, place large, heavy duty pan or Dutch oven over medium heat. Add several inches vegetable oil and heat to 350°F.
Working with one egg roll wrapper at a time, moisten edges with water. Place wrapper with one point facing toward you. Place about 1/4 cup macaroni and cheese in center and roll corner closest to you over filling. Fold in sides of wrapper and continue rolling until it is closed. Press to seal and set aside. Continue with remaining wrappers and macaroni and cheese.
Place egg rolls in heated oil and fry, turning occasionally, until golden brown. Remove and drain on paper towels or wire rack. Serve warm.