Pre-heat your oven (Gas mark 4/ 180c) and line an 9 inch square baking tin with baking paper/ parchment paper.
Melt the butter and dark chocolate together in the microwave in short bursts. Stir until smooth, then let cool slightly. (This may take 2-3 minutes).
In a separate bowl (I recommend using a stand mixer but an electric hand whisk will work too). Add in your sugar and eggs and whisk on high for 10 minutes until the mixture is light and fluffy.
Pour your melted chocolate/butter mixture into the egg mixture. (If using a stand mixer, change to a paddle attachment. If using an electric hand whisk, change to a spatula and fold the melted mixture in). Mix the chocolate mixture with the egg mixture on a low speed until in-cooperated.
Add in your vanilla, double cream , golden syrup and sift in the flour, cocoa powder, and salt. Gently fold until just combined. Don’t over-mix!
Fold in the custard cream biscuits. You can also sprinkle a few extra on top.
Pour into a lined 8x8 inch (20cm) square tin and smooth the top. Bake for 25–30 minutes, or until the edges are set but the centre is still soft. Don’t over-bake, your brownies will have a slight wobble in the middle).
Refrigerate for 3 hours or preferably overnight! This will make your brownies fudgy and delicious!
Slice and Eat!
