Preheat oven to 425 degrees. Grease a 9-10” pie pan or cast iron pan.
Place shredded sweet potatoes in a bowl and cover with water. Use your hands to mix around and release the starches (your water will turn orange!). Drain sweet potato, and squeeze excess water out using your hands, paper towel or cheese cloth. Place in a clean, dry bowl.
Add flour, garlic powder, parmesan cheese, salt, pepper and egg white. Mix to evenly combine.
Press the sweet potato mixture on the bottom and about 2” up the sides. Firmly press into the pan using your hands.
Bake for 20-25 minutes until light golden and crispy. Set aside to cool.
Heat butter over medium-low heat in large skillet. Add sliced onions and a pinch of salt. Cook, stirring occasionally until onions start to brown, about 10 minutes.
Just as the onions are softened and light brown, add the tomato halves. Continue cooking until the onions are golden and caramelized. about another 10 minutes.
While onions are cooking, whisk together eggs, milk, parmesan cheese, pepper, garlic powder and onion powder. Set aside.
Once the onions are caramelized and the tomatoes are softened, add in the baby spinach and cook another 3-5 minutes until the spinach is wilted.
Add veggies to the sweet potato crust and spread evenly. Then pour egg mixture on top.
Top with goat cheese crumbles and bake 25-30 minutes until egg has set.
*The filling can be made up to 2 days ahead and kept in the refrigerator.