Preheat your oven 175 C (fan).
In a large mixing bowl, mix oats, sunflower seeds, pumpkin seeds and Amaranth.
Chop the nuts with a knife or pulse them in a food processor for 20 seconds (not too small if you like it crunchy and nutty). Add them in the large bowl with oats and seeds. Set aside.
If the dates are very dry or hard, soak them first for 10 to 15 minutes in hot water. Then remove the water and add the moist dates (pitted), with the cinnamon, vanilla, salt and the optional syrup in a food processor (or a small blender) and pulse until smooth liquid. If you have the impression that it is still too hard add some water (1-2 tbsp at a time) and mix again. It should be kind of smooth (but not runny) and with few pieces (it will be tastier).
With a wooden spoon, mix well the date paste with the dry ingredients until it is totally combined. It might take a little while (and a bit of muscles) to fully mix both together.
Spread evenly your granola on a lined baking tray. Put it in the oven for approximately 20-30 min by 175°C or until toasty brown. Give it a stir every 10 minutes and check how brown it is to make sure it is not burning.
Switch off the oven and open the door to let it cool down in the oven, for an extra crunch.
Store in an airtight container for up to 2-3 weeks.