Place the pitas on a lightly greased baking sheet. If desired, cover each with 1/4 cup tomato sauce. The recipe works without the sauce as well.
In a medium size bowl, place the baby spinach that has been washed, dried and loosely cut into smaller pieces.
Add your olive oil of choice, and mix to coat the leaves thoroughly. Divide the mixture evenly over the 4 pitas.
In another bowl, combine, ham & pineapple and balsamic vinegar. Coat well and evenly distribute over the spinach layer of the pitas.
Lastly, top each with 1/4 cup of cheese, and season to taste with the red pepper flakes and salt.
After baking for 10 or 15 minutes, check to see if cheese has melted and is starting to bubble & brown. If so, a nice finishing touch at this point is a drizzle of an additional 1 teaspoon olive oil over each pita, and a return to the oven for a final few minutes and a final crisp.