In a bowl, combine the ricotta and pesto. Set aside.
On a work surface, put a lettuce leaf on each four slices of bread. Cover with the chicken. Spread with the ricotta pesto. Season with salt and pepper. Garnish with the tomatoes and remaining lettuce leaves. Cover with the other slices of bread. Cut the sandwiches in half.
Serve the sandwich with the Winter Vegetable Minestrone Soup.
Ricotta cheese replaces mayonnaise in this sandwich. Combined with the pesto, it becomes a delicious spread.