📖 Instructions

1. **Prepare the Brownie Batter:** In a heatproof bowl set over a simmering pot of water (double boiler), melt 100g of dark chocolate and 50g of unsalted butter. Stir until smooth. Be careful not to let the bowl touch the water.
2. Remove from heat and whisk in 75g of granulated sugar until well combined.
3. Beat in one large egg, followed by 1 teaspoon of vanilla extract. Don't overmix at this stage!
4. In a separate bowl, whisk together 50g of all-purpose flour and 1/4 teaspoon of salt. Gently fold this dry mixture into the wet ingredients until just combined. The batter should be thick and fudgy.
5. **Make the Macaron Shells:** In a food processor, grind 100g of almond flour with 100g of powdered sugar until very fine. Sift the mixture to remove any large particles. This is crucial for smooth shells!
6. In a clean, dry mixing bowl, whisk 75g of egg whites with 1/4 teaspoon of cream of tartar until stiff peaks form. Gradually add 50g of granulated sugar while whisking, until the meringue is glossy and stable.
7. Gently fold the almond flour mixture into the meringue in two additions. This process is called 'macaronage.' Be careful not to overmix, as this will deflate the meringue and result in flat macarons. The batter should flow like lava, forming a ribbon when dropped from the spatula.
8. Divide the macaron batter in half. Gently fold in 2 tablespoons of the brownie batter into ONE half of the macaron batter until just combined.
9. Transfer both macaron batters (plain and brownie swirl) into separate piping bags fitted with a round tip.
10. Pipe even circles onto baking sheets lined with parchment paper or silicone mats. Aim for about 1.5 inches in diameter, leaving some space between each macaron.
11. Tap the baking sheets firmly on the counter several times to release any air bubbles. This helps prevent cracking during baking.
12. Let the macarons rest at room temperature for 30-60 minutes, or until a skin forms on the surface. You should be able to gently touch the surface without the batter sticking to your finger.
13. **Bake the Macarons:** Preheat your oven to 300°F (150°C). Bake the macarons for 12-15 minutes, or until they have 'feet' (the ruffled edge at the bottom) and are firm to the touch. Rotate the baking sheets halfway through baking for even cooking.
14. Let the macarons cool completely on the baking sheets before removing them. They should easily lift off the parchment paper or silicone mat when cooled.
15. **Prepare the Chocolate Ganache Filling:** Heat 100ml of heavy cream in a saucepan until simmering. Pour it over 150g of chopped dark chocolate. Let it sit for a minute, then stir until smooth and glossy. Let the ganache cool and thicken slightly.
16. **Assemble the Macarons:** Pair up macaron shells of similar sizes. Pipe or spread a dollop of chocolate ganache onto the flat side of one shell and sandwich it with another shell. Repeat with the remaining macarons.
17. Refrigerate the assembled macarons for at least 24 hours before serving. This allows the flavors to meld together and the shells to soften slightly.