4 ounces bittersweet chocolate, chopped fine
1 teaspoon instant coffee or espresso powder [see note] 1 tablespoon hot water
1/2 cup sweetened condensed milk
1/2 teaspoon vanilla extract
1 1/4 cups cold heavy cream
fleur de sel [for sprinkling]
Combine coffee powder and hot water in a small bowl. Let stand until coffee dissolves, about 5 minutes. Microwave chocolate, sweetened condensed milk and coffee mixture in a large bowl, stirring every 10 seconds, until chocolate is melted, about 1 minute. Stir in vanilla and salt. Let cool.
With a standing mixer, whip cream on medium high until soft peaks form. Whisk one third of whipped cream into chocolate mixture. Fold remaining whipped cream into chocolate mixture until incorporated. Freeze in an airtight container until firm, at least 6 hours or up to 2 weeks.