Place bread slices topped with cheese on a baking sheet. Heat in oven at 250 degrees.
Drain chicken and place in a skillet. Dice onions and tomatoes and add to chicken along with Italian salad dressing and picante sauce, pepper and dill weed. Turn burner on to medium. Cook until heated thoroughly, stirring often.
When cheese has melted, remove bread from oven. Lay spinach leaves over the cheese and top with chicken and tomatoes. Serve warm.
