Preheat your oven to 180°C and line a 24 x 18cm baking dish with greaseproof paper.

Place all the ingredients except for the muesli into a small saucepan. Place over medium heat and allow to melt, stirring occasionally.

Measure the muesli into a large mixing bowl.

When the butter and golden syrup mixture starts to bubble and foam, allow to cook for 30-40 seconds, then remove from the heat and pour it straight over the muesli.

Mix well with a spatula until all the cereal is coated in the syrup, then tip the flapjack mixture into the prepared baking dish.

Use the spatula to compress the mixture into an even layer, pressing firmly as this will help to compact it for easy cutting later.

Place into the centre of your oven and bake for 12-14 minutes until the cereal is lightly golden on top. Remove from the oven and allow to cool completely before cutting.

Once cooled, use a large sharp knife to cut the flapjacks into bars. Store in an airtight container until ready to serve.