Heat the oven to 350 degrees F. Grease and line with greaseproof paper one 10-inch
springform or loose-bottomed tin.
Beat the butter with an electric whisk until the butter is soft.
Add sugar and
beat until perfectly smooth and light and fluffy.
Beat all the eggs together separately,
and add very slowly to prevent the cake mix curdling.
Sdd in the Calvados.
Core the apple and chop finely, leaving the skin on. Fold the apple flesh into the cake
Sift the flour into the cake and apple mix, and fold in gently.
Transfer to the cake tin, level and bake in the centre of the oven, undisturbed if possible,
for 45 minutes, or until the top springs back when touched. Note that a knife inserted
into the cake may not come out perfectly clean because of the apple.
Cool the cake in the tin for a few minutes before turning out to cool on a wire
To finish: If the cake is quite thick, it is possible to cut it as a sandwich
cake. If you do this, use 9 ounces of butter and sugar for the topping and filling
mix, instead of 6 ounces. Slice the cake into two layers with the longest, thinnest
knife you have.
Beat the butter until soft and creamy and then beat in the confectioners'
sugar until it is light and fluffy. Stir in the Calvados. If you are sandwiching
the cake, fill with a thin layer of icing first, and stick the two layers together.
To get a better level, it is usual to put the top of the cake in the middle. Spread
the icing on top of the cake smoothly. Roll the icing into balls (about walnut size),
slice the balls in half and press into the icing.