In a large microwave-safe bowl, mix your add-ins: rolled oats, sultanas, desiccated coconut, almonds, pepitas, sesame seeds, salt, and cinnamon. Stir well to combine.

In a small saucepan over medium heat, combine peanut butter and honey. Stir constantly until the mixture is fully blended and bubbling slightly on the edges. Lower the heat and cook for 5 minutes, stirring without walking away. You want it thickened to a caramel consistency that holds a path when you scrape the bottom.

Working quickly, pour this hot mixture over your prepared dry ingredients. Stir with a sturdy wooden spoon, using a pressing and smearing motion to coat everything evenly. If it becomes too thick to mix, microwave the bowl for 20 seconds to re-loosen.

Line a 20cm (8") square tin with parchment paper. Press the mixture firmly into the pan using the back of a spoon or your hands. The firmer you press, the chewier the bars will be.

Refrigerate for at least 2 hours, or until set. Once chilled, use a sharp knife to cut into 10 even bars.