Pre-heat the oven at 170ºC.
In a mixing bowl, add the nuts (You can lightly chop them up), the oats, the peanut butter and maple syrup.
Mix super well, making sure all the ingredients are well-mixed and forming kinda like a paste. It is going to be a bit hard to mix, but keep on going.
In the lined tray, add all the mixture and line it all gently into an even layer. With the help of a spoon, break the mixture into some chunks, but don't go crazy (like I did), or you'll end up with very small chunks.
Put the tray in the oven and cook for about 20 minutes. Mid-way through the cooking time, shake a bit the tray so the chunks move a bit.
Take it out of the oven when you start seeing the granola chunks golden a bit. Let it cool down for around 30 minutes, or just store it in an air-tight container and use it later.