Prep & Dry Mix

1. Line 2 baking sheets with silicone mats or parchment; fit a piping bag with a 10 mm round tip.
2. In a food processor combine almond flour, ground pistachios and powdered sugar; pulse until very fine, then sift into a bowl; discard large bits left in the sieve.
3. Measure out egg whites and bring to room temperature (about 20–30 minutes) before whipping.

Make Meringue & Macaronage

1. In a clean bowl whisk egg whites with cream of tartar and salt on medium speed until foamy.
2. Gradually add granulated sugar while increasing speed to high; whip to stiff, glossy peaks (stiff but not dry).
3. Add gel coloring to the meringue and whisk briefly to distribute color evenly.
4. Fold one-third of the dry mix into the meringue to loosen, then fold in remaining dry mix in 2 additions using a spatula: scrape bottom and fold until batter flows in a thick ribbon and smooths back into the bowl in about 10–15 seconds (macaronage).

Pipe, Tap & Rest

1. Transfer batter to the piping bag and pipe 3–4 cm rounds spaced 2–3 cm apart on prepared sheets; tap trays firmly 2–3 times on the counter to remove air bubbles.
2. Let piped shells rest at room temperature until a dry skin forms on top (30–60 minutes depending on humidity); they should not stick to your finger.
3. Preheat oven to 150°C (300°F) while shells are resting.

Bake & Cool

1. Bake one sheet at a time on middle rack for 14–16 minutes, rotating once halfway through if your oven runs hot; shells are done when they have feet and do not jiggle.
2. Let baked shells cool completely on the tray before removing to avoid cracking.

Make White Chocolate-Lemon Ganache

1. Put chopped white chocolate into a heatproof bowl.
2. Heat cream until it just begins to simmer, then pour over white chocolate; let sit 1–2 minutes without stirring.
3. Stir gently until smooth, then whisk in butter, lemon zest and lemon juice until glossy; cool to room temperature, then chill 1–2 hours until pipeable.

Assemble & Finish

1. Pair shells by size; transfer ganache to a piping bag fitted with a 6–8 mm tip.
2. Pipe about 10–12 g ganache onto the flat side of one shell and sandwich with its pair, pressing gently to spread to the edge.
3. Optional: roll edges lightly in chopped pistachios or sprinkle extra lemon zest on top.
4. Refrigerate assembled macarons in an airtight container for at least 24 hours for best texture and flavor; bring to room temperature 20–30 minutes before serving.