Put the oats, flour, baking powder and salt into a bowl and mix. Preheat the oven to 180 C.
Put the golden syrup, butter and sugar in a saucepan, gently heat and stir until the butter is liquid and the sugar has dissolved. Add the moist ingredients to the dry ones and stir until combined.
Butter and line a 30cm x 40cm baking tray. Spread the mixture across the bottom of the tin using a metal spoon.
Bake for 25-30 minutes, or until golden brown. Let rest for 10 minutes before cutting into bars.