Preheat the oven to 180 C / Gas 4. Line a baking tray/tin with greaseproof paper.
Melt the butter, sugar and syrup in a pan on a low/medium heat. Remove from the heat and add in your oats. Stir them in thoroughly ensuring the mixture covers all the oats. Place the mixture into the tin.
Bake in the preheated oven for roughly 20 minutes until golden brown. (Mine usually comes out a couple of minutes before). Leave to cool and cut into slices.