In a large bowl, combine the whole wheat flour, vital wheat gluten, mixed seeds, and salt. Stir well to evenly distribute the dry ingredients.
In a separate small bowl, whisk together the warm water (approximately 100°F), honey, and active dry yeast. Allow the mixture to sit for about 5 minutes until it becomes frothy.
Add the Greek yogurt and whey protein powder to the dry ingredients and mix briefly.
Pour the yeast mixture into the dry ingredients and stir until a shaggy dough forms.
Turn the dough onto a lightly floured surface and knead for about 8-10 minutes until smooth and elastic. If the dough is too sticky, sprinkle a little extra flour as needed.
Place the kneaded dough in a lightly oiled bowl, cover with a damp towel, and let it rise in a warm area for about 1 to 1.5 hours, or until doubled in size.
Preheat the oven to 375°F (190°C). Lightly grease a small loaf pan.
Punch down the dough, shape it into a loaf, and transfer it to the prepared pan. Cover again and let it rest for another 20 minutes for a second rise.
Bake in the preheated oven for 25-30 minutes until the top is golden brown and the loaf sounds hollow when tapped.
Remove from the oven and let the bread cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.