Heat oven on Bake at 350 degrees.
Place frozen spinach and garlic along with 1/2 cup of water in a small sauce pan on medium high heat for 5 minutes or until cooked. In a medium mixing bowl, mix drained spinach mixture and ricotta cheese. Separate each pita enough to place ricotta mixture inside. Do not separate the pita completely. Spread 1/2 cup of mixture evenly throughout each pita. Slightly press pita.
Now it's time to dress your pita pizza. Spread 1/2 cup of sauce on each pita round. Add Mozzarella cheese, sliced tomatoes and sliced artichoke hearts.
Place Pizza on Pizza stone or cookie sheet and place in the 350 degree oven for about 10 minutes or until pita is toasted and cheese is melted.