Line a 12-section bun tray with paper cake cases. Put the almonds in a food processor and process until ground.
Tip the ground almonds into a bowl and add the butter, caster sugar, eggs, flour and baking powder. Beat well using a hand-held electric whisk for about a minute until light and creamy.
Stir in the glacé cherries and then divide the cake mixture between the paper cases.
Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 25 minutes or until risen and just firm to the touch. Transfer to a wire rack to cool.
Press the jam through a sieve to remove any lumps and spread over the tops of the cakes. Beat the icing sugar in a bowl with the water to make a thick icing that almost holds its shape. Spread a little over each cake and decorate with the cherry halves.