Make the Macaron Shells

1. Prepare baking sheets.
   Line two baking sheets with parchment paper or silicone mats. Fit a piping bag with a round tip.
2. Sift dry ingredients.
   In a bowl, sift the almond flour and powdered sugar together twice to remove any lumps and achieve a fine texture. Discard large pieces that don’t pass through the sieve.
3. Make the meringue.
   In a clean, grease-free mixing bowl, beat the egg whites on medium speed until foamy. Gradually add granulated sugar and continue beating until stiff, glossy peaks form. Add vanilla extract and a few drops of green gel coloring; mix until evenly tinted.
4. Fold the batter (macaronage).
   Gently fold the dry mixture into the meringue using a rubber spatula. Fold until the batter flows like “lava” — it should fall off the spatula in thick ribbons and settle into itself within 10 seconds.
5. Pipe the macarons.
   Transfer the batter to your piping bag and pipe small 1½-inch rounds onto the prepared baking sheets. Tap the trays firmly on the counter 4–5 times to release air bubbles. Add gold and white sprinkles or edible stars to the tops.
6. Rest the shells.
   Let the piped macarons rest at room temperature for 30–40 minutes, or until they form a dry, non-sticky skin when gently touched.
7. Bake.
   Preheat the oven to 300°F (150°C). Bake one sheet at a time for 14–16 minutes, rotating halfway through. The macarons are done when they have “feet” and can be gently lifted from the parchment.
8. Cool completely.
   Allow the shells to cool completely before removing them from the baking mats. Handle gently — they’re delicate!

Make the Buttercream Filling

1. Beat butter.
   In a medium bowl, beat the softened butter until light and creamy (about 2 minutes).
2. Add sugar and flavoring.
   Gradually add powdered sugar, beating until smooth. Add vanilla extract, heavy cream, and a pinch of salt. Beat for another 2 minutes until fluffy.
3. Optional flavor boost.
   For a Christmas Tree Cake-inspired filling, fold in marshmallow fluff or drizzle in white chocolate ganache.
4. Pipe and assemble.
   Pair macaron shells by size. Pipe a small dollop of buttercream on one shell and gently sandwich with another. Press lightly to spread the filling evenly.
5. Mature the macarons.
   For best texture, refrigerate assembled macarons in an airtight container for at least 24 hours before serving. Bring to room temperature before eating.