Easy Chocolate Mousse with Croissant Crumbs

Heat sugar and ¾ cup whipping cream in a small saucepan over medium, stirring often, until sugar is dissolved, about 3 minutes. Remove from heat. Add chocolate chips and vanilla; stir until melted and smooth, about 2 minutes. Let cool for 10 minutes.

Meanwhile whisk remaining 1¼ cups whipping cream in a large bowl until medium peaks form, about 2 minutes.

Add chocolate mixture to whipped cream in 3 batches, gently folding after each addition until just combined and no streaks remain. Spoon mixture evenly into serving dishes; cover each dish loosely with plastic wrap. Chill for 2 hours for a lighter texture or up to 8 hours for a denser, richer texture. (Mousse can be made up to 3 days ahead and chilled in an airtight container; spoon into serving dishes before serving.)

Meanwhile, preheat oven to 300°F. Process croissant pieces in a food processor until fine crumbs form, about 30 seconds. Spread crumbs in an even layer on a rimmed baking sheet. Bake, tossing crumbs and rotating baking sheet halfway through, until golden brown and crisp, 12 to 14 minutes. Let cool completely, about 15 minutes. (Croissant crumbs can be made up to 3 days ahead and stored in an airtight container.)

Before serving, if mousse chilled longer than 2 hours, let come to room temperature for 30 minutes. Top with croissant crumbs and flaky sea salt.