Prepare the Dry Ingredients: Sift together the almond flour and powdered sugar twice to remove lumps and achieve a fine texture. Set aside.
Make the Meringue: In a clean, dry bowl, beat the egg whites on medium speed until foamy. Add cream of tartar (if using), then gradually add the granulated sugar, a little at a time. Continue beating until stiff, glossy peaks form. Add vanilla extract and yellow food coloring; gently mix to combine.
Macaronage (Folding the Batter): Add the sifted dry mixture to the meringue in three parts. Using a silicone spatula, fold the batter gently by scraping around the bowl and pressing through the center. Continue folding until the batter flows like lava — it should fall from the spatula in thick ribbons and slowly settle into itself within 10 seconds.
Pipe the Shells: Transfer the batter into a piping bag fitted with a round tip (½ inch). Pipe small circles (about 1.25–1.5 inches) onto parchment-lined baking sheets. Tap the tray gently on the counter several times to release air bubbles. Let the piped shells rest 30–60 minutes at room temperature until the tops are dry to the touch.
Bake: Preheat oven to 300°F (150°C). Bake one tray at a time for 12–16 minutes, rotating halfway. Shells are done when they have “feet” and do not wobble when touched. Cool completely before removing from parchment.
Make the Pineapple Buttercream: In a mixing bowl, beat butter until light and creamy (about 2 minutes). Add powdered sugar gradually, beating until fluffy. Mix in pineapple juice, crushed pineapple, extract (if using), and salt. Beat until smooth — add a bit more powdered sugar or juice to adjust texture.
Assemble: Match up shells of similar size. Pipe a small swirl of pineapple buttercream onto one shell and top with another to make a sandwich. Gently press together until the filling just reaches the edges.
Mature & Serve: Place assembled macarons in an airtight container in the refrigerator for 24–48 hours to mature — this allows the shells to soften slightly and the flavors to meld.Bring to room temperature before serving.
