Heat oven to 180C/160C fan/gas 4.
Grease and line a 20cm square baking tin.
Whisk together the butter, sugar, eggs,
flour and custard powder until well
combined and fluffy. Spread into the tin
and bake for 25-30 mins until golden and
risen. Cool in the tin.
Remove cooled cake from tin and
spread with the jam. Trim the edges,
then cut into 16 squares. Add a meringue
to each just before serving.