Prepare the Macaron Shells:

1. Prepare Baking Sheets: Line two baking sheets with parchment paper or silicone mats. You can use a template to ensure your macarons are evenly sized.
2. Sift Dry Ingredients: In a bowl, sift together the powdered sugar and almond flour. This step is crucial to ensure smooth macaron shells. Set aside.
3. Whip Egg Whites: In a clean bowl, beat the egg whites with a hand mixer or stand mixer on medium speed until foamy. Add the cream of tartar, and then gradually add the granulated sugar. Continue beating on high speed until stiff peaks form. If desired, add a few drops of gel food coloring to achieve a pink hue for the shells.
4. Fold in Dry Ingredients: Gently fold the sifted almond flour and powdered sugar mixture into the whipped egg whites using a spatula. Be careful not to overmix or undermix; the batter should flow slowly off the spatula in a ribbon-like consistency.
5. Pipe the Macarons: Transfer the macaron batter to a piping bag fitted with a round tip. Pipe small rounds (about 1-inch in diameter) onto the prepared baking sheets, spacing them about 1 inch apart.
6. Rest the Shells: Let the macarons sit at room temperature for 30-60 minutes to form a skin. This helps prevent cracking during baking.
7. Preheat the Oven: Preheat the oven to 300°F (150°C) during the resting period.
8. Bake the Shells: Bake the macarons for 15-18 minutes, rotating the pans halfway through. The shells should be firm to the touch and have a smooth, glossy surface. Let them cool completely on the baking sheets before removing.

Prepare the Raspberry Pistachio Ganache:

9. Toast the Pistachios: In a dry skillet, lightly toast the pistachios over medium heat for about 3-5 minutes, or until fragrant. Let them cool, then pulse them in a food processor until finely ground.
10. Make the Ganache: In a saucepan, heat the heavy cream until it just begins to simmer. Remove from heat and add the chopped white chocolate, stirring until it melts completely.
11. Add Raspberry and Pistachio: Stir in the ground pistachios, fresh raspberries, butter, vanilla extract, and a pinch of salt. Mix until smooth and well combined. Let the ganache cool to room temperature, then refrigerate for about 30 minutes to firm up.
12. Whip the Ganache: Once chilled, use an electric mixer to whip the ganache until it becomes light and fluffy.

Assemble the Macarons:

13. Pipe the Ganache: Once the macaron shells have cooled completely, pipe a small amount of the raspberry pistachio ganache onto the flat side of one shell.
14. Sandwich the Macarons: Gently press another macaron shell on top to form a sandwich. Repeat until all macarons are assembled.
15. Let Them Mature: Place the assembled macarons in an airtight container and let them sit in the fridge for at least 24 hours. This allows the flavors to meld and the texture to develop.