Rinse the buckwheat and soak it in water overnight.
Drain and rinse the soaked buckwheat, then blend it with ½ cup of water until smooth.
In a bowl, combine the blended buckwheat, honey, ground flaxseed, salt, and baking powder. Stir until fully incorporated.
Pour the batter into a greased or parchment-lined loaf pan. Sprinkle the top with poppy seeds, flax seeds, and everything bagel seasoning.
Preheat the oven to 375°F and bake for 1 hour 15 minutes, or until a toothpick inserted into the center comes out clean.
Let the bread cool in the pan for 10 minutes before transferring it to a wire rack. Slice and enjoy!