Prepare the Brownies:
Preheat your oven according to the directions on your brownie mix. Prepare the brownies as directed on the box (or your homemade recipe). If you’re using chocolate chips, fold them into the brownie batter before baking. Bake according to package instructions, then cool completely.

Make the Fudge Layer:
In a small saucepan, heat the heavy cream over medium heat until it just starts to simmer. Remove from heat and add the chocolate chips and butter, stirring until smooth and glossy. Let the fudge cool to room temperature before using.

Prepare the Raspberry Layer:
In a small bowl, toss the fresh raspberries with the powdered sugar (if using) to sweeten them. Set aside.

Whip the Cream:
In a large mixing bowl, whip the heavy cream with powdered sugar and vanilla extract until stiff peaks form. Be careful not to overwhip.

Assemble the Trifle:
Cut the cooled brownies into bite-sized cubes. In a large trifle dish or individual serving cups, layer the brownies, raspberry mixture, fudge sauce, and whipped cream. Start with a layer of brownies, followed by a layer of fudge sauce, then some raspberries, and top with whipped cream. Repeat the layers until the dish is full, finishing with a layer of whipped cream on top.

Chill and Serve:
Refrigerate the trifle for at least 2 hours (or overnight) to let the flavors meld together. Just before serving, garnish with extra fresh raspberries and chocolate shavings, if desired.