Preheat the oven to 160C Fan and line 3 baking trays with greaseproof paper.
Place the ground almonds, granulated sugar, honey, almond extract and egg whites in a bowl.
Beat with a flexible spatula or wooden spoon to make a thick paste.
Place the bowl over a saucepan filled with simmering water, making sure the water does not touch the base of the bowl.
Remove the bowl from the heat and scoop out two tablespoons of the paste and reserve it.
Place the remaining paste in a piping bag fitted with a 1cm straight piping nozzle and pipe 2.5cm mounds, piping 20 on each baking sheet.
Dampen some kitchen roll/paper towels and lightly place them on the macarons to moisten them. Remove the paper towels and dust the mounds with icing sugar.
Bake for around 20 minutes, the tops will crack, but they're meant to. Carefully pour 100ml of water underneath the greaseproof paper and leave the macarons to cool completely on the baking sheets.
Transfer the macarons onto a baking sheet, so they are upside down, spread a small amount of the reserved paste onto the flat side of half the macarons and sandwich together with a plain macaron.
You will have 30 macarons in total.