Step 1: In a microwave-safe bowl, melt the semi-sweet chocolate chips in 30-second intervals, stirring between each until smooth and creamy. Set aside to cool slightly.
Step 2: In a large, chilled bowl, whip the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.
Step 3: Gently fold the slightly cooled melted chocolate into the whipped cream until fully combined, being careful not to deflate the mousse.
Step 4: Divide the chocolate mousse evenly among individual serving cups or glasses. Place in the refrigerator.
Step 5: In a small saucepan, combine the chopped cherries, granulated sugar, cornstarch, and water. Mix well.
Step 6: Bring the mixture to a boil over medium heat, stirring constantly.
Step 7: Reduce the heat to low and simmer for about 5 minutes, or until the compote has thickened. Let it cool slightly.
Step 8: Spoon the cooled cherry compote evenly over the chocolate mousse in each cup.
Step 9: (Optional) Top with whipped cream and garnish with fresh cherries.
Step 10: Chill for at least 1 hour before serving to allow flavors to meld and mousse to set. Enjoy!