01 - Line two baking sheets with parchment paper or silicone mats. Fit a pastry bag with a 1/2-inch round tip.
02 - Sift almond flour and powdered sugar together into a bowl. Set aside.
03 - Whisk egg whites and cream of tartar in a clean, dry bowl until soft peaks form. Gradually add granulated sugar while whisking until stiff, glossy peaks form.
04 - Gently fold almond flour mixture into meringue in three additions. Tint one-third of batter yellow if desired. Mix until batter flows in thick ribbons.
05 - Transfer batter to pastry bag. Pipe 32 rounds about 1.5 inches each onto prepared sheets. Tap trays firmly to release air bubbles.
06 - Let shells rest at room temperature 30-60 minutes until dry to touch. Preheat oven to 300°F. Bake 13-15 minutes, rotating halfway, until shells lift easily from mat. Cool completely.
07 - Heat cream until simmering. Pour over chocolate, let sit 2 minutes, then stir smooth. Add golden syrup and butter, mix until glossy.
08 - Reserve one-quarter of filling and tint with yellow gel. Chill both fillings until thickened.
09 - Pipe a ring of chocolate filling on one shell, place a dollop of yellow filling in center. Sandwich with another shell. Repeat with remaining macarons.
10 - Store assembled macarons in airtight container overnight to allow flavors to mature fully.