Step 1

Preheat oven to 350 degrees F. Coat a 9-by-5-inch loaf pan with cooking spray. Line the bottom of the pan with parchment paper.

Step 2

Combine sunflower seeds, pumpkin seeds, flaxseeds and sesame seeds in a medium dry skillet; toast over medium heat, stirring, until light brown and starting to pop, 5 to 7 minutes.

Step 3

Reserve 2 tablespoons of the seed mixture in a small bowl; transfer the remaining seeds to a large bowl. Add almond flour, coconut flour, baking powder, baking soda and salt to the large bowl; whisk to combine. Whisk eggs, buttermilk, oil, chia seeds and maple syrup (if using) in a medium bowl. Stir the wet ingredients into the dry ingredients until combined. Scrape the batter into the prepared pan. Sprinkle with the reserved seeds, pressing them gently into the batter to help them adhere. Let stand for 10 minutes.

Step 4

Bake the loaf until golden brown and a toothpick inserted in the center comes out clean, about 40 minutes. Let cool in the pan on a wire rack for 30 minutes before turning out onto the rack to cool completely.