Preheat oven to 170°C and place two unlined baking trays on the middle shelves.
Melt 60g of chocolate in a bowl over simmering water without letting the bowl touch the water.
Combine icing sugar, ground almonds, and two egg whites into a paste.
Fold the melted chocolate into the paste and set aside.
Whisk two egg whites and lemon juice on medium speed in a mixer.
Cook sugar and water in a pan until it reaches 117°C.
Slowly pour the hot syrup into the whipped egg whites while mixing at low speed.
Increase speed to high and whisk for 3 minutes.
Fold the meringue into the chocolate paste until it reaches the ribbon stage.
Transfer the mixture to a piping bag with an 8mm nozzle.
Pipe 3cm discs onto greaseproof paper, spaced 2cm apart.
Slide the paper onto the pre-heated baking trays.
Bake for 8 minutes and transfer to a rack to cool completely.
Bring whipping cream to a boil in a small pan.
Whisk 100g of chocolate into the hot cream until smooth and place in a piping bag.
Pipe 5ml of ganache onto one macaroon and sandwich with another.
Store the assembled macaroons in an airtight container in the fridge.