In a small saucepan over low heat combine the cheese, cornstarch and milk, salt and pepper and heat, stirring constantly, until the cheese is melted. It will probably be a little stringy. Beat the egg yolks lightly for a few seconds, the add about 1/4 cup of the cheese mixture and beat vigorously. Pour the egg mixture slowly into the cheese mixture, beating constantly, and continue cooking the cheese mixture over low heat, stirring constantly, until it becomes runny and smooth. Ladle it immediately into ramekins or small soup bowls. Stand the toast triangles around the inside of the bowls and serve immediately.