Mix the oats, nuts and cinnamon in a large bowl.
In a pot, gently warm the date syrup (or honey), apple puree, peanut butter and coconut oil over medium heat. Heat just until everything comes together. It should not boil.
Pour the warm mixture over the dry ingredients and stir until everything is coated.
Spread the granola on a baking tray lined with parchment paper.
Bake at 150-160°C (300-320°F) for 30-35 minutes. Stir once around the 10-15 minute mark, then leave it alone so the clusters stay big. Keep an eye on it and lower the temperature if it browns too fast. It may look a bit soft when it comes out, but it hardens as it cools.
Let it cool completely on the tray, then break it into pieces and store it in a glass jar.