Prep the pan and oven: Preheat your oven to 350°F (175°C). Line a 9x5-inch loaf pan with parchment paper, leaving some overhang for easy lifting. Lightly grease the sides.
Mix dry ingredients: In a large bowl, whisk almond flour, ground flaxseed, coconut flour, chia seeds, baking powder, baking soda, and salt until evenly combined and lump-free.
Whisk wet ingredients: In a separate bowl, beat the eggs.
Add almond milk, oil, vinegar, and sweetener (if using). Whisk until smooth.
Combine: Pour the wet mixture into the dry ingredients. Stir with a spatula until a thick, spreadable batter forms.
Fold in 1/2 cup sunflower seeds.
Pan and top: Spread the batter into the loaf pan, smoothing the top with a spatula. Sprinkle the remaining sunflower seeds over the surface and gently press them in.
Bake: Bake for 40–50 minutes, or until the top is golden and a toothpick inserted in the center comes out clean or with a few moist crumbs. If the top browns too quickly, tent loosely with foil.
Cool: Let the bread cool in the pan for 15 minutes.
Lift it out using the parchment and cool completely on a wire rack before slicing. This sets the structure.
Slice and serve: Use a sharp, serrated knife to cut into 12–14 slices. Enjoy plain, toasted, or topped with butter, avocado, or sugar-free jam.