Preheat oven to 350F and coat a 9-inch pie plate with avocado oil
Peel sweet potatoes and cut very thinly. Line the bottom of the plate with about 3-4 layers of sweet potato rounds. For the sides of the "crust" that line the upward rims of the pie plate, cut the rounds in half so the bottom has a straight edge and the tops are circular. Again, overlap so that the entire plate is covered, Brush all sweet potato rounds with avocado oil.
Bake the "crust" for 20 minutes.
In a pan, saute onions until browned and add in riced cauliflower and broccoli. Sprinkle in salt and pepper. Add in the spinach and saute. Lastly, add in the garlic and combine until fragrant.
Pour the above vegetable mix into the sweet potato "crust".
Slice tomatoes and sprinkle flour and basil on them. Put these in the saute pan with a bit more avocado oil and cook until soft.
Add tomatoes on top of the vegetables in the "crust".
In a bowl, mix the milk with eggs. Once completely combined, pour into quiche.
Bake in the oven at 400F for 18 minutes or until eggs are cooked through.