Whisk almond flour, coconut flour, 6 tablespoons sunflower seeds, psyllium husk, flaxseed meal, baking powder, and salt together in large bowl. Whisk water, eggs, and melted butter together in separate bowl. Stir egg mixture into flour mixture until well combined. Scrape batter into prepared pan. Smooth top, mounding batter Scrape batter into prepared pan. Smooth top, mounding batter Scrape batter into prepared pan. Smooth top, mounding batter seeds, pressing gently to adhere. Cover and let sit at room temperature for 30 minutes.