Position a baking rack in the center of your oven and preheat to 325°F (160°C). Line a large baking sheet with parchment paper and lightly grease the paper.
In a spacious mixing bowl, combine the almond flour, coconut flour, protein powder, chopped rosemary, baking powder, salt, and garlic powder. Whisk these dry ingredients thoroughly to ensure even distribution.
Introduce the olive oil, whole eggs, and egg whites to the dry mixture. Blend with a sturdy spoon or spatula until a cohesive dough begins to form.
Gradually incorporate water, starting with ⅓ cup, and mix until a soft, slightly sticky dough is achieved. Add up to an additional ¼ cup of water by the teaspoonful if needed to reach the desired consistency.
Transfer the dough onto the prepared baking sheet. Using moistened hands, gently press and spread the dough into a roughly 10.5 x 15.75 inch rectangle, aiming for an even thickness.
Use the tips of your fingers to create shallow indentations across the surface of the dough. Sprinkle generously with flaky sea salt and arrange fresh rosemary sprigs over the top.
Bake in the preheated oven for 28 to 33 minutes, or until the edges are nicely golden brown and the surface feels firm when lightly touched.
Allow the baked bread to cool on the baking sheet for at least 15 minutes before slicing and serving.