Creating Chocolate Coffee Mousse Trifles is a fun and simple process. Follow these steps to achieve the perfect dessert:

1. Melt Chocolate: In a microwave-safe bowl, melt the semi-sweet chocolate chips in 30-second intervals, stirring between each until smooth. Allow it to cool slightly.
2. Whip Cream: In a mixer, whip the heavy cream until soft peaks form. Add in the vanilla extract and mix briefly to combine.
3. Make Mousse Base: In a separate bowl, whisk egg whites with granulated sugar and salt until stiff peaks form.
4. Combine Ingredients: Gently fold the melted chocolate into the whipped cream until just combined. Then carefully fold in the egg whites until no streaks remain.
5. Flavor with Coffee: Slowly incorporate the brewed coffee into the mousse mixture, being cautious not to deflate the mixture.
6. Prepare Serving Dish: In your trifle bowls or glasses, layer the mousse and ladyfinger cookies/graham crackers alternately. Start with a layer of mousse, then add a layer of cookies.
7. Repeat Layers: Continue layering until the glasses are filled, finishing with mousse on top.
8. Chill: Cover with plastic wrap and refrigerate the trifles for at least 2 hours to allow them to set.
9. Garnish: Before serving, dust the top with cocoa powder or add chocolate shavings for an elegant touch.

By following these straightforward steps, you will create a dessert that is not only delicious but also visually stunning.