In the top of a double boiler, combine the cream, cheddar, white pepper, and nutmeg. Stir over hot water until the cheese melts and the mixture is well blended. Remove from the heat and cool to lukewarm. Generously butter a large baking sheet and set aside. Cut the bread slices diagonally and dip each triangle into the cheddar mixture. Place 1 cm apart on the baking sheet and bake until browned and bubbly, about 15 minutes. Serve hot.