I made this frosting this afternoon and it's cooled and spreadable, only thing is it has small lumps of chocolate in it that don't seem to have melted completely.
Can I reheat it to melt the lumps? Would it be better to heat it over water like a double boiler or in the microwave?
1 cup whipping cream
1/2 cup unsalted butter, cut into 1/2-inch pieces
1/3 cup sugar
1/4 cup water
2 teaspoons instant espresso powder
1/4 teaspoon salt
16 ounces semisweet chocolate, finely chopped
1 teaspoon vanilla extract
Simmer cream, butter, sugar, water, espresso powder, salt. Add chocolate and stir until melted, whisk in vanilla. Cool until spreadable, about three hours.