Preheat oven to 350 F. Spray a 9x13 baking dish with cooking spray. In a medium bowl, combine sweet potatoes and zucchini. Drizzle with the olive oil and sprinkle with 1/2 tsp salt. Toss the vegetables around to coat. Let this sit for at least 15 minutes.
In another bowl, whisk together eggs, cream, salt, hot sauce, and Mrs. Dash seasoning. Place the zucchini and sweet potatoes mixture on the greased baking dish. Add the spinach, spreading it in an even layer. Pour the liquid mixture over everything. Sprinkle the shredded cheese on top.
Bake at 350 F for 45-55 minutes, or until the eggs are set and the top is lightly golden.
To make this ahead, follow the instructions except the sprinkling of cheese. Cover the baking dish with plastic wrap and chill in the fridge overnight. The next morning, sprinkle the cheese and bake.