In a food processor, grind 100 grams of almond flour and 200 grams of powdered sugar until fine. Sift the mixture into a large bowl and set aside.
In a separate bowl, whisk 3 egg whites (at room temperature) with a pinch of salt until frothy. Gradually add 50 grams of granulated sugar and continue whisking until stiff peaks form.
Gently fold the almond flour mixture into the egg whites using a spatula, until the batter is smooth and flows like lava.
Fill a piping bag with the batter and pipe small circles (about 3 cm in diameter) onto a baking sheet lined with parchment paper. Tap the baking sheet on the counter to release any air bubbles.
Allow the piped macarons to rest at room temperature for 30-60 minutes, until a skin forms on the surface.
Preheat the oven to 150°C. Bake the macarons for 12-15 minutes, until they have risen and the feet have formed. Allow them to cool completely on the baking sheet.
Prepare your desired filling (e.g., buttercream, ganache, or jam) and pipe it onto the flat side of one macaron. Sandwich it with another macaron, gently pressing them together.
Refrigerate the macarons for at least 24 hours to allow the flavors to meld. Bring them to room temperature before serving.