In a medium bowl blend cream cheese, sour cream and mayonnaise with an electric mixer until smooth. Stir in 1/2 the Swiss cheese, Parmesan cheese, parsley, spring onions and garlic.
Arrange bread slices in a single layer on a medium baking tray. Lightly toast under the grill. Remove from heat.
Spread French bread slices with the cream cheese mixture. Sprinkle with remaining Swiss cheese. Broil under the preheated grill approximately 1 1/2 minutes until cheese is melted. Remove from heat and sprinkle with ground black pepper.