Preheat oven to 160C. Spread almonds over a baking tray and bake for 7 minutes or until lightly coloured. Cool, then blend in a food processor to a coarse powder. Stir in flour and set aside.
Combine butter and milk in a saucepan and stir over low heat until melted. Whisk in sugar, remove from heat and cool.
Whisk in cloves, baking powder, vanilla and egg, stir into almond mix, until just combined, then chill for 1 hour or until easy to handle.
Preheat oven to 160C. Roll a tablespoonful of almond mixture into a ball and place onto a baking paper-lined oven tray. Repeat with remaining mixture. Bake for 35-40 minutes or until golden brown. Cool on tray for 10 minutes, then transfer to a wire rack.
Meanwhile, for glaze, combine sugar and 175ml water in a saucepan and bring
to the boil, then simmer for 3 minutes. Whisk in icing sugar and lemon rind until smooth.
Immerse warm biscuits in glaze, then place on a wire rack over an oven tray to cool. Serve topped with lemon zest. Biscuits will keep in an airtight container for up to one week.