- With the rack in the middle position, preheat the oven to 180 °C (350 °F). Line two baking sheets with parchment paper.
- In a food processor, process the almonds and icing sugar into fine powder, about 2 to 3 minutes. Set aside.
- In a bowl, beat the egg whites with the food colouring until soft peaks form. Gradually add the sugar, beating constantly until stiff peaks form. With a spatula, firmly combine with the ground almonds mixture and mix until the meringue fall and soften slightly.
- With a pastry bag fitted with a 7-mm (1/2-inch) in diameter plain tip, shape 2.5-cm (1-inch) in diameter macarons, spacing them about 5-cm (2-inch) apart. (The batter should fall slightly. Otherwise, it is not quite soft enough. Remove from the bag and mix again). Hit the baking sheet flat on a work surface two or three times to slightly spread the batter.
- Bake, one sheet at a time, for about 12 minutes, leaving the oven door ajar with a wooden spoon. The macarons should not brown. Cool completely on the baking sheet. (For smaller macarons, bake from 8 to 10 minutes. They should therefore be baked on two different baking sheets.)
- In a saucepan, combine all the ingredients. Bring to a boil, stirring constantly.
- Attach a candy thermometer in the centre of the pan and simmer until the thermometer reads 104 °C (219 °F). Skim carefully and stir frequently while cooking. Let cool completely.
- Place the cooled jam in a sieve and let drain for 5 minutes.
- Fill the macarons with a little jam and close like a sandwich. They are usually filled at the last moment, because macarons filled with jam tend to soften rapidly. Eat while the inside has softened slightly, but the outside must remain crisp.