Preheat the oven to 300F.
In a large bowl, combine the sunflower seed flour, Parmesan, rosemary, garlic powder, and salt.
Stir in the egg white and butter until the dough comes together.
Turn the dough out onto a large silicone baking mat and pat into a rough rectangle.
Top with a large piece of parchment paper. Roll out to about a ¼ to ⅛-inch thickness, as evenly as you can.
Remove the parchment.
Use a sharp knife or pizza cutter to score into 1 to 2-inch squares.
Sprinkle with coarse sea salt.
Transfer the baking mat to a large baking sheet.
Bake 30 to 40 minutes, or until the edges are golden brown and the crackers are firm to the touch.
Remove and let cool completely before breaking apart. They will continue to crisp up as they cool.
If the edges are browning before the center pieces firm up, you can break them off and allow the rest to keep cooking.
