Place shredded zucchini and onion in a salad spinner. Sprinkle with kosher salt and let mixture stand 30 minutes to allow the water to draw out. Spin mixture to remove as much excess water as possible. Then transfer to a kitchen towel or several layers of paper towels to remove any additional water.
Cook bacon in a medium skillet over medium high heat until crisp. Remove bacon from skillet using a slotted spoon and reserve remaining bacon drippings.
In a separate bowl, mix together egg, garlic, Italian seasoning, and baking powder. Add in zucchini mixture and cracker crumbs. Measure out about 1/3 cup of the dough and form into a patty. Repeat until you have made about eight patties.
Pour cornmeal into a shallow bowl. Coat patties on both sides with the cornmeal.
Preheat oven to 170 degrees.
Add 1 tablespoon of oil to the reserved bacon drippings. Heat oil over medium high heat. Gently place cakes into the oil and fry until golden brown on the outside, about 4 minutes per side. Transfer cakes to a plate lined with paper towels. Add additional oil as needed during frying.
Once the zucchini cakes have drained, place the cakes on a cookie sheet and top with a slice of mozzarella. Place in the oven and warm just until the cheese has melted, about five minutes.
To assemble, place one cheese-topped zucchini cake on a plate. Layer with a tomato slice and then one or two basil leaves. Repeat layers, ending with a zucchini cake. Garnish with a basil leaf if desired.