Step 1: Preheat the Oven

Preheat your oven to 160°C (320°F) and line a 23cm square baking tin with parchment paper, leaving some overhang to easily lift out the flapjacks later.

Step 2: Melt the Butter, Sugar, and Syrup

In a large saucepan, melt the butter, light brown sugar, and golden syrup over medium heat. Stir frequently until the butter is fully melted and the sugar has dissolved, forming a smooth mixture.

Step 3: Add the Condensed Milk and Vanilla

Once the butter and sugar mixture is melted, reduce the heat to low and stir in the condensed milk and vanilla extract (if using). Keep stirring gently for a few minutes until the condensed milk is fully incorporated and the mixture becomes smooth and glossy.

Step 4: Mix in the Oats

Remove the saucepan from the heat and stir in the rolled oats, ensuring that they are fully coated with the buttery, sugary mixture. Mix well until the oats are evenly distributed.

Step 5: Transfer to the Baking Tin

Pour the oat mixture into the prepared baking tin and press it down evenly using the back of a spoon or spatula. Make sure the flapjack mixture is spread evenly across the tin for consistent baking.

Step 6: Bake the Flapjacks

Place the baking tin in the preheated oven and bake for 25-30 minutes, or until the edges are golden brown and the center is slightly firm to the touch. The flapjacks will continue to set as they cool, so don’t worry if they seem a little soft when you take them out.

Step 7: Cool and Slice

Once baked, remove the tin from the oven and allow the flapjacks to cool completely in the tin. Once cooled, lift them out using the parchment paper overhang and transfer them to a cutting board. Slice into squares or rectangles and serve.