1. Preheat oven to 375°F (190°C). Line two baking sheets with parchment paper.

2. In a large bowl, mix rye flour, wheat flakes, graham flour, and dark syrup until well combined and crumbly.

3. In another bowl, whisk buttermilk, all-purpose flour, salt, and baking soda until smooth.

4. Pour the wet mixture into the dry ingredients and stir until a shaggy dough begins to form.

5. Gradually add the film milk, 1 cup at a time, mixing with a wooden spoon or your hands until the dough comes together.

6. Turn the dough onto a lightly floured surface and knead for 5 minutes until smooth and elastic, adding a little more flour only if sticky.

7. Divide the dough into two equal portions. Shape each into an oblong loaf and place on the prepared baking sheets.

8. Press sunflower seeds evenly into the top of each loaf.

9. Bake for 35 to 40 minutes, rotating pans halfway, until deep golden brown and hollow-sounding when tapped on the bottom.

10. Transfer loaves to a wire rack and cool completely before slicing, at least 1 hour.