Line an 8x8" glass baking dish with parchment paper. This will help easily remove the fudge once it is set.
In a glass microwavable mixing bowl, add the butter, brown sugar and Dulce de leche flavored caramel sauce. Microwave for 10 minutes, stirring every 2 minutes, scraping the sides of the bowl well. Then let cool for a few minutes.
In a small glass bowl, add the chocolate chips. Cook on high in the microwave for 1 minute, then stir. Cook for another 30 seconds, then stir. Repeat in 30 second intervals until smooth.
Stir the melted chocolate chips into the melted caramel. Then gently stir in the instant coffee granules and the coarse sea salt. Stir with an electric beater for 3 minutes, or whisk aggressively for 3 minutes.
Then spread the mixture into the prepared baking dish. Sprinkle some coarse sea salt over the top.
Chill in the refrigerator for about 2 hours, or until set.
Remove the fudge from parchment paper and baking dish. Place on a cutting board and slice with a sharp knife into 1" square pieces. Makes 48-64 pieces, depending on how large you slice the pieces.