Preheat oven to 350F.
Slice eggplants in half, lengthwise.
Score the eggplant flesh with a sharp knife, then scoop out the flesh with a spoon leaving about 1/2" of flesh on the shell. Reserve the flesh.
Heat oil in a large saute pan, add the onion and the Italian seasoning, saute until the onion becomes translucent.
Add the ground beef, breaking it up with a wooden spoon and stir until browned and cooked through.
Add the tomatoes and season with salt to taste.
Fill the eggplant shells with the meat mixture and top each with the Parmesan cheese.
Place shells on a baking sheet with about 1/4 cup of water. Bake for about 20 minutes until the shells are cooked through.