Mix the warm water, milk, agave syrup, yogurt, salt, and vegetable oil in a bowl. Add the wheat flour, rye flour, spelled flour, bran, mashed potatoes powder, and dry yeast. Knead using a bread maker or by hand for about 5 minutes until a dough forms. Let rest for 5 minutes.
Place the dough on a work surface. Stretch and fold the dough. Let rest for 15 minutes.
Cut the dough into individual pieces and shape each into a roll. Place on a floured towel and let rest for 10 minutes.
Preheat the oven to 220°C (428°F) with top and bottom heat. Place rolls in and bake for 25-30 minutes at 220°C (428°F), brushing with water or milk every 5 minutes. After 12-15 minutes, reduce the temperature to 180°C (356°F) and continue baking.
Optional: For freezing, partially bake rolls for 10-15 minutes at 220°C (428°F), cool completely, and freeze. To bake from frozen, place in a cold oven and bake at 200-220°C (392-428°F) for 15-20 minutes.