Preheat your oven to 180°C (160°C Fan, gas mark 4) and line two medium baking trays with parchment paper. If you have a large baking tray, then you just need one.
Add butter, golden syrup and light brown sugar to a large mixing bowl and melt in the microwave on a medium heat.Check every 10 to 15 seconds and give the mixture a stir. Repeat until the mixture has melted.
Add self-raising flour, porridge oats, bicarbonate of soda and cinnamon to the melted butter mixture and mix together until thoroughly combined.
Scoop a tablespoon of dough and roll it into a ball using the palms of your hands. Place the ball onto the lined baking tray. Repeat this step for the remaining dough; leave a gap between each ball.
Gently press the dough with your fingers to flatten it slightly.
Bake in the oven for 10 to 15 minutes or until golden brown. Leave the biscuits to cool down for 5 minutes before removing them from the baking tray.