Preheat the oven to 400 degrees F. Put rack in top 1/3 of the oven.
Grease a 9.5 inch round tart dish. ( I like to use ceramic tart dish). Lay out the sliced sweet potatoes in the dish, filling in as much space as possible. Cut some of the slices in half to use along the sides of the pan. Spray the tops of the sweet potatoes with an olive oil spray. Bake the sweet potato crust for 20 minutes.
While the sweet potato crust is baking, put 1 Tablespoon of olive oil into a large frying pan over medium heat. Add the minced shallot and garlic to the pan, and cook for 2-3 minutes, mixing every so often.
Add the shredded zucchini and kale to the pan, mix them into the shallots and garlic and then let it all cook for 4-8 minutes, until a lot of the liquid from the zucchini is evaporated. Stir every so often. Set the veggies aside.
Then, in a medium bowl, mix the eggs, milk, salt, pepper, and nutmeg together with a whisk.
Add the zucchini and kale to the egg mixture, along with the cheese (if adding), and mix. Pour the whole thing into the sweet potato crust.
Top the quiche with the sliced cherry tomatoes.
Reduce the oven heat to 375 degrees F. Put the quiche into the oven for 30 minutes. Remove from the oven and let the quiche sit for 10-15 minutes.