Add the oats, hazelnuts, sunflower seeds, sesame seeds, flax seeds, and chia seeds to a large mixing bowl. Add in the salt and give it a good mix.
Pour the boiling water on top and give it a good stir. Let sit on the counter for 20 minutes.
Preheat the oven to 400°F (200°C).
Grease a rectangular loaf pan and/or line it with parchment paper.
Give the oat and seed mixture another stir and transfer it to the loaf pan. Use a spatula to press it down tightly into the pan.
Bake for 70 minutes at 400°F (200°C), fan.
Let cool for 10 minutes, then transfer the bread to a cooling rack. Let it cool completely before slicing (this is very important).
Notes
Avoid silicon molds. When I tested the recipe, the silicone pan didn't hold its shape, making the bread large and flat.
Don't change the quantities of oats, flax seeds, or chia seeds. They act as binding ingredients and keep the bread together. However, feel free to swap out the hazelnuts, sunflower seeds, and sesame seeds for other nuts and seeds.
Toast the bread to make it crunchy.
Storage tips: store the bread in a large air-tight container on the counter for 1-2 days and in the refrigerator for an additional 1-2 days.
Freezing tips: cut the bread into slices and freeze them for up to 3 months.