Preheat your oven to 300°F (150°C). Line two baking sheets with parchment paper or silicone baking mats.
In a bowl, sift together the almond flour and powdered sugar. In a separate mixing bowl, whisk the egg whites with a pinch of salt until foamy. Gradually add the granulated sugar and continue whisking until the mixture reaches stiff peaks. If you'd like, add a few drops of pink gel food coloring during this process.
Gently fold the sifted almond flour and powdered sugar into the egg whites using a rubber spatula. Use a figure-eight motion until fully incorporated and the mixture flows like lava. Be careful not to over-mix—stop when the batter starts to slowly fall off the spatula.
Transfer the batter to a piping bag fitted with a round tip. Pipe small circles onto the prepared baking sheets, leaving space between each macaron. Tap the baking sheets on the counter to release any air bubbles, and let the macarons sit at room temperature for about 30-60 minutes, until the tops are no longer sticky.
Once dried, bake the macarons in the preheated oven for 15-20 minutes, or until the feet have formed and the tops are crisp. Let them cool completely before removing from the sheets.
In a mixing bowl, beat the softened butter until smooth. Gradually add 2 cups of powdered sugar and continue to mix until well combined. Add the vanilla extract and mix until creamy. If you'd like, you can add a bit of raspberry puree to the buttercream for extra flavor.
Flip half of the macaron shells upside down. Pipe a generous dollop of the buttercream filling on each upside-down shell. Top with a few fresh raspberries and gently press another macaron shell on top to create a sandwich.
Optionally, sprinkle a few finely chopped pistachios on the sides of the macarons for a decorative touch.
Notes
For best results, ensure egg whites are at room temperature.