Add 1 cup chocolate chips and ½ cup heavy cream to a medium bowl. Microwave about 60 seconds, then stir until fully smooth and glossy. If a few chips remain, keep stirring; the residual heat usually finishes the melt.

Let the bowl sit about 15 minutes. You want it cool to the touch but still pourable. If it’s warm, it can thicken or seize when the whipped cream hits it.

In a stand mixer bowl, whip 1 cup heavy cream, ¼ cup powdered sugar, and ½ teaspoon vanilla until stiff peaks form. It should look smooth and hold its shape, not grainy.

Scoop about half of the whipped cream into a piping bag with a large star tip. Refrigerate it so it stays firm.

Add the remaining whipped cream into the cooled chocolate. Fold gently with a spatula until the color is even and the texture looks airy. Stop once combined.

Spoon into serving cups. Eat right away for a softer texture, or chill 2 hours for a firmer set.

Pipe the reserved whipped cream on top and sprinkle 1 tablespoon chocolate jimmies.