Preheat the oven to 190/375/gas 5, grease a 18 x 30cm baking tin (don't worry if you don't have one this exact size, just adjust your baking times if it is much bigger or smaller)
Heat the golden syrup, honey, peanut butter black treacle and butter in a large saucepan.
When all is melted and well combined, mix in all the other ingredients and stir well until all of the oats are well coated.
Tip out into the greased tin, level out then press down firmly with the back of a spoon.
Bake for 20 minutes, or until the top is golden brown and smelling divine.
Run a knife around the outside of the tin, loosening the sides, then score into squares (I got 16 squares, but you can make them any size you like). Let cool in the tin, then prise out of the tin to eat/store.