Line a 20cm square tin with baking paper. Heat the oven to 190°C/170°C fan (375°F).
In a large bowl, mix the oats, flour, brown sugar, ginger, baking powder and salt.
Melt together the butter and golden syrup then mix into the bowl of dry ingredients. Press into the base of the tin in an even layer.
Bake for 25-30 minutes, until it has a good golden crust. Leave to cool completely in the tin.
For the topping, melt the butter and golden syrup together. Sift the icing sugar, ginger and salt into a large bowl then add the molten mixture.
Beat with an electric whisk on medium-high speed for 2-3 minutes until it is thick and fudgy. Spread over the cooled base, and leave to set.
Remove from the tin and cut into 16 squares or bars.
