Cut off the tops of the tomatoes and scoop out just the pulp, leaving the walls intact. Pour the juice of the tomatoes into a measuring cup to reserve 1/4 cup. Sprinkle the inside of each tomato with salt and turn upside down onto a paper towel.
Heat oil in a large saucepan over medium heat. Add spinach and garlic, saute for about 2 minutes. Then add reserved tomato juice and wine. Let cook for another few minutes.
Remove saucepan from heat. Now add Parmesan, feta and panko breadcrumbs. Mix well. Add more panko if needed.
Spoon this mixture evenly into each tomato til slightly over flowing, as in photo.
Bake uncovered on middle rack for about 30-35 minutes. Keep an eye on them so that they don't brown too much. Then remove from oven.
Allow them to cool slightly. Serve warm.
These can also be made using cherry tomatoes and served as orderves.