For the base: Mix all dry ingredients together and then add the eggs and melted butter and mix until combined.
Line a baking tray with baking paper, grease, and pack two thirds of the mixture into it. (The last third of the base mix will be used in the final step. Put aside while making the filling.)
Melt butter, condensed milk, golden syrup and vanilla extract together and whisk until smooth. Pour over the packed base in the baking tray.
Sprinkle chocolate drops evenly over the filling and then crumble the remaining base over the top.