Preheat the oven to 350 degrees Fahrenheit. Line an 8x8 inch with parchment paper, or grease heavily with butter.
In a large pot, heat the butter, brown sugar, and golden syrup over medium heat, stirring constantly, until the butter is melted and the sugar has dissolved.
Remove from heat and stir in the oats until coated.
Pour the mixture into the prepared pan and spread out evenly. Bake for 25 minutes, or until golden brown (the edges will be slightly darker). Remove from heat and slice into 8 triangles. Let cool completely before removing from pan.