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. Optionally tint one-third of batter yellow. Mix until batter flows in thick ribbons (macaronage stage).
05 - Transfer batter to pastry bag. Pipe 32 rounds approximately 1.5 inches in diameter onto prepared sheets. Firmly tap trays to release air bubbles. Let shells rest at room temperature for 30-60 minutes until surfaces are dry to touch.
06 - Preheat oven to 300°F. Bake for 13-15 minutes, rotating trays halfway through. Shells are done when they easily lift off the mat. Cool completely before filling.
07 - Heat heavy cream until just simmering. Pour over chopped milk chocolate and let stand for 2 minutes. Stir until smooth. Add golden syrup and butter, mixing until glossy and emulsified.
08 - Separate one-quarter of the filling and tint with yellow gel coloring to mimic egg yolk. Refrigerate both portions until thickened to piping consistency.
09 - Pipe a ring of chocolate filling onto one shell. Place a small dollop of yellow filling in the center. Gently sandwich with another shell. Repeat with remaining shells.
10 - Store assembled macarons in an airtight container overnight at room temperature to allow flavors to mature and texture to develop.