Preheat oven to 150°C and line a tray with silicone paper marked with 4cm circles.
Pulse almonds with icing sugar and sieve to remove large pieces.
Whisk egg whites with salt until frothy, then add caster sugar gradually until glossy peaks form.
Fold egg whites and food coloring into the almond mixture until it reaches a ribbon consistency.
Pipe mixture into circles and let set for 15 minutes.
Bake for 12 to 15 minutes and cool on a wire rack.
Increase oven temperature to 200°C and grease 4cm silicone moulds with butter and flour.
Whisk egg and sugar until frothy, then mix in butter, flour, lemon zest, juice, and baking powder.
Rest batter for 20 minutes before baking in moulds for 12 to 15 minutes.
Cool sponges for 10 minutes then dip into limoncello.
Boil lemon juice and sugar for 5 minutes until syrupy and let cool.
Blend blueberries to a purée, sieve into a pan, and sprinkle with agar-agar.
Heat mixture for 5 minutes, pour into a lined tin, and chill until set.
Blend set jelly with lemon juice to create a gel and transfer to a piping bag.
Mix granulated sugar, citric acid, and coloring to make sherbet.
Brush sponge edges with syrup, roll in sherbet, and pipe gel into a small hole in the top.
Pipe whipped cream over the hole and top with a macaroon sandwiched with remaining gel.