Simmer all the ingredients together in a small pan for about ten minutes or until the apples are soft.
Blend into a rough purée with a stick blender.
Cream the butter and sugar together until light and fluffy.
Beat in the eggs, one at a time.
Sift in the dry ingredients and stir gently in.
Fold in 1 heaped tbsp of the apple purée.
Place 1 tsp of batter into each muffin case (24 in total), add a scant tsp of apple purée than top up with another tsp of batter so the muffin is slightly over 3/4 full.
Bake at 180℃ (350℉, Gas 4) for 15-20 minutes when the cakes should be well risen and firm to the touch but not too brown.
Rub the butter and sugar into the flower with fingertips until the mixture resembles breadcrumbs. Add the water and stir with a knife until the mixture clumps together.
Spread out onto a baking tray and bake at 180℃ (350℉, Gas 4) for 15 minutes or so until golden.
Allow to cool.
Beat the ingredients together in a bowl until well combined and light in texture. Add a drop of milk if the mixture is too stiff.
Spread onto the cooled cakes and top with a little crumble.
Adapted from Primrose Bakery Christmas by Martha Swift.Makes 12 regular sized cupcakes or 24 mini cakes.Please note: calories and other nutritional information are per serving. They're approximate and will depend on exact ingredients used.