Combine all the ingredients from batch #1 in the bowl of a stand mixer (or a large bowl) and cover with plastic wrap or a clean towel. Let sit for at least 2 1/2 hours at room temp, or overnight if you can. This will expand the seeds and make them chewy, which will help bind them to the dough.
After the mixture from batch #1 has been sitting for several hours or overnight, add in the ingredients from batch #2, perhaps holding back a bit of the flour. Fit the dough hook of the stand mixer on and mix for 5 minutes at low speed, then increase to high speed and knead the dough for another 5 minutes. Add more flour if necessary, until you get a smooth, elastic dough.
Let the dough rest for another 2 hours. Prepare three loaf pans by greasing them lightly with oil. Then pour the dough onto a clean work surface, divide it into three equal pieces. Fit the pieces into each loaf pan (if you don’t have loaf pans you can also free bake them by shaping the pieces into loaves and placing them onto a baking sheet).
Cover the loaves with a clean towel, and let rest for another 45 minutes at room temp. Meanwhile, heat your oven to 440° Fahrenheit (220° Celcius).
Brush the top of the loaves with a little water, and sprinkle additional chia, sunflower and pumpkin seeds on top. Bake for about 30-35 minutes or so until the bottom is hard and make a hollow noise when you tap them.
Cool for about an hour (if you can wait) before slicing into it. Serve with vegan butter and a cup of coffee or tea!