Preheat the oven to 375℉ (190℃).
Slice the focaccia in half horizontally. Lightly drizzle or brush olive oil on the cut sides (optional, but it helps with toasting and flavour).
Remove the skin and shred the rotisserie chicken into small bite-size pieces. Layer the shredded chicken over the bottom half of the focaccia.
Add the cheese on top of the chicken. Toast for 5-6 minutes, until edges are lightly crisp and cheese is melted.
Make the Italian salad: Add the lettuce to a medium bowl. Finely dice the shallot and add it to the bowl. Drizzle in the dressing and toss gently until everything is evenly coated.
Mash the avocado in a small bowl until smooth (this makes it easier to spread). Once the bread is toasted and removed from oven, spread the avocado evenly over one half. Spoon the Italian salad onto the other half, then place the top piece of bread on and gently press down.
Cut into portions and serve whole, or deconstructed for younger children.