1) Melt the chopped caramel(s) with the heavy cream in a small saucepan set over low heat. Stir until smooth, then set aside to cool to lukewarm.
2) Place the butter, confectioners' sugar, meringue powder (if using), vanilla extract, and sea salt in the bowl of your stand mixer. Beat on low speed for about 1 minute, just to combine. The mixture will still be quite lumpy.
3) Add the cooled caramel to the butter/sugar in the bowl. Beat on low speed for 1 minute to incorporate the caramel into the mix. If the mixture is quite thick, add milk or cream as needed to thin to a blend-able consistency.
4) Increase the speed to high and beat the icing for 5 minutes. You'll see bits of caramel throughout the icing at first; these will melt into the icing over the long mixing time. The meringue powder will increase the fluffiness of the icing as well.
5) Spread the icing on cupcakes, cakes, brownies, even cookies. Add an extra sprinkle of sea salt on top if desired, or drizzle with additional caramel. Store leftover icing in the fridge for up to 1 week.
Yield: about 4 cups icing.