In a large bowl, combine the sunflower seed flour, Parmesan, rosemary, garlic powder, baking powder and salt.
Stir in the egg and butter until 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 2 inch squares. Sprinkle with coarse sea salt. Transfer to a large baking sheet.
Bake 40 to 45 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.
Recipe makes about 40 crackers, depending on how thinly you roll the dough.