Dissolve coffee powder in hot water.
Stir well and set aside.
Thaw refrigerated unsalted butter. Add
icing sugar and beat till fluffy and pale yellow.
Beat egg yolks together. Pour beaten egg
yolks into butter, half the amount at a time.
Stir in coffee and coffee liqueur. Sift
in cake flour, corn flour and baking powder. Toss in chopped walnuts
and mix well to form batter.
Whisk egg whites till frothy (without
stiff peaks formed). Add sugar a little at a time and mix well. Pour
in batter over 3 times and mix well.
Pour mixture into baking tray lined with
grease-proof paper till 80% full. Level with spatula and lightly
compact. Bake at 170 degrees Celsius for 18 to 20 minutes.