Preheat oven to 450 degrees.
Spray baking pan with baking spray, or use silicone mat on pan.
Use meat mallet to beat chicken until about 3/4″ thick.
Season with salt & pepper to taste.
Heat 1/2 tbsp oil in medium skillet over medium heat. Add garlic and saute for about 1 minute.
Add spinach, 1 tbsp of lemon juice and 1/2 tsp salt. Saute until spinach is wilted, about 2 minutes. Remove from heat.
At the largest part of the chicken, layer each slice of chicken with 1/2 slice of mozzarella, prosciutto, and spinach.
Roll chicken starting with the largest part and rolling in.
In a medium sized bowl, mix panko, 1/4 tsp pepper, and sage. In a second medium sized bowl, mix 3 tbsp lemon juice and 3 tbsp olive oil.
Dip rolled chicken in lemon/olive oil mixture, then roll in panko mixture.
Place rolled chicken on prepared pan, seam side down.
Spray tops of chicken lightly with baking spray (I use vegetable oil spray).
Bake for 20-25 minutes, or until cooked through.