Preheat the oven to 350°F (180°C). Grease a 9x5-inch (23x13-cm) loaf pan with nonstick spray.
Cut the cauliflower into florets and add to a food processor. Pulse until the cauliflower reaches a “rice”-like consistency. You should have 3-4 cups. (900 g)
Transfer the riced cauliflower to a large microwave-safe bowl and microwave for 4 minutes to steam the cauliflower and release its liquid. Let sit until cool enough to handle.
Transfer the riced cauliflower to a bowl lined with cheesecloth or a tea towel. Tightly wrap the cauliflower and squeeze out all of the liquid, until it is dry and crumbles between your fingers. Set aside.
Separate the yolks and whites of the eggs into two large bowls. Beat the whites with an electric hand mixer until stiff peaks form.
Add about ¼ of the beaten whites to the bowl of yolks. Then, add the almond flour, Parmesan, if using, garlic, baking powder, butter, and salt. Gently mix with a rubber spatula until combined.
Add the remaining egg whites, dried cauliflower, and Italian seasoning. Gently fold the ingredients together until just combined. Do not overmix, as this will break down the egg whites.
Transfer the mixture to the prepared loaf pan and sprinkle the top with sesame seeds, parsley, and rosemary.
Bake for 45-50 minutes, or until the bread is golden brown.