Preheat oven to 375
Cut of tops of heirloom tomatoes and hallow out the centers with a pairing knife
Sautee garlic and baby spinach together on a low heat. The spinach will cook super fast, so be cautious in not over cooking it.
Drain baby spinach in a small colander.
Fill each tomato with baby spinach, and then place in a hand formed tart shell. I used a mini-cheesecake pan that holds up to 12, but you can also use a mini muffin tray OR just hand form them onto a piece of parchment paper on a cookie sheet.
Top each tomato tart with feta cheese on top and then place in the oven for approximately 15 minutes, or until crust is a light golden brown color.
Allow to cool and serve!