01 - Line two baking sheets with parchment paper or silicone mats. Fit a piping bag with a round tip approximately 3/8 inch opening.
02 - Pulse almond flour and powdered sugar in a food processor until extra fine. Sift into a large bowl and discard any coarse particles.
03 - In a clean, grease-free bowl, whip egg whites with cream of tartar until foamy. Gradually add granulated sugar while whipping until stiff peaks form. Add pink gel food coloring and mix until evenly distributed.
04 - Gently fold the sifted almond mixture into the meringue in three additions using a spatula. Continue folding until batter flows in thick ribbons with lava-like consistency. Avoid overmixing.
05 - Transfer batter to piping bag. Pipe 1.2-inch rounds onto prepared sheets, spacing 3/4 inch apart. Tap trays firmly on counter to release air bubbles. Pop any visible bubbles with a toothpick.
06 - Let macarons rest uncovered for 30 to 45 minutes until tops are dry to the touch and a slight skin forms.
07 - Preheat oven to 300°F. Bake one tray at a time for 12 to 15 minutes, rotating halfway through. Shells should rise to form feet and remain pale without browning.
08 - Remove baked macarons from oven and let cool completely on baking sheets before removing from parchment.
09 - Beat softened butter until creamy. Gradually add sifted powdered sugar and mix until fluffy. Fold in strawberry puree, vanilla extract, and salt. Beat until smooth and uniform in color.
10 - Pipe or spoon buttercream onto flat side of half the shells. Top with remaining shells, pressing gently to form sandwiches.
11 - Refrigerate assembled macarons in an airtight container for at least 24 hours to allow flavors to develop and shells to soften slightly. Bring to room temperature before serving.