1Preheat the oven to 350°F (175°C). Grease and line an 8-inch square baking pan with parchment paper.
2In a bowl, whisk together the melted butter and sugar until smooth.
3Add the eggs one at a time, then stir in the vanilla extract.
4Fold in the cocoa powder, flour, and salt until just combined. Stir in the chocolate chips.
5Spread the batter evenly into the prepared pan and bake for 22–25 minutes, or until the center is just set. Allow the brownie to cool completely.
6Melt the dark chocolate with 100 ml of the heavy cream over low heat or in the microwave in short intervals. Stir until smooth and let cool to room temperature.
7Whip the remaining 200 ml heavy cream with the powdered sugar and vanilla until soft peaks form.
8Gently fold the cooled chocolate mixture into the whipped cream until light, smooth, and fluffy.
9Crumble the cooled brownies into bite-sized pieces.
10Spoon a layer of brownie crumbles into the bottom of each serving glass.
11Add a generous layer of chocolate mousse over the brownie pieces.
12Repeat the layers once more, finishing with a swirl of chocolate mousse piped on top.
13Garnish with chocolate shavings, chocolate curls, and a sprinkle of brownie crumbs.
14Refrigerate for at least 2 hours before serving for the best texture and flavor.