Preheat oven to 450. Line a baking sheet with nonstick foil and spray heavily with cooking spray. Place flour and sliced zucchinis in a large plastic bag, seal and toss to coat the zucchini.
Place panko crumbs in one small bowl and whisked eggs in another bowl. Combine salt, black pepper, garlic powder and chili powder in a third bowl and whisk to mix well. Dip flour-coated zucchini slices in the whisked eggs, then toss them in the panko crumbs. Dip them a second time in the egg and a a second time in the panko.
Place all zucchini slices on prepared baking sheet in a single layer. Sprinkle half of the seasoning mixture over the zucchini slices and spray with cooking spray.
Bake about 5-6 minutes until tops of zucchini fries begin to brown. Remove from oven, carefully flip over all of the zucchini slices, sprinkle with remaining seasoning and return to oven. Cook another 4-5 minutes until browned. Remove and allow to cool slightly.
Mix together mayo, sriracha, and garlic powder until smooth. Serve with zucchini fries. Enjoy!