Whisk the egg whites until stiff. Gradually whisk in the sugar until the mixture is thick and glossy. Gently fold in the ground almonds and grated chocolate.
Line a large baking sheet with nonstick baking paper. Put the mixture in a piping bag fitted with a large plain nozzle and pipe small rounds, about 4 cm (1½ inches) in diameter, on to the baking sheet. Alternatively, place small teaspoonfuls on the baking sheet.
Press a chocolate coffee bean into the centre of each macaroon. Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for about 15 minutes until slightly risen and just firm. Leave the macaroons on the baking paper to cool.