To prepare olive salad, combine first 8 ingredients in bowl of a food processor. Process 30 seconds or until finely chopped; chill.
To prepare muffuletta, cut rolls in half horizontally. Cut each cheese slice in half crosswise. Spread about 2 1/2 tablespoons olive mixture onto top half of each roll. Layer 1/2 cup greens, 1/2 cheese slice, 1 roast beef slice, and 1 chicken slice on each roll bottom; cover with top of roll.
Wrap each sandwich tightly in plastic wrap. Chill up to 8 hours.