Step 1. Preheat oven to 350°. Line a 9-inch square cake pan with wax paper or foil, draping over the edges. Lightly butter the lining.
Step 2. In a large saucepan, melt the butter with the unsweetened chocolate over very low heat, stirring occasionally. Remove from the heat. Whisking in the remaining ingredients excluding the MiaBella Fleur de Sel one at a time until thoroughly incorporated.
Spread batter in to the 9-inch pan. Sprinkle the MiaBella Fleur de Sel Sea Salt over the batter. Using a skewer(or butter knife) swirl the salt into the batter.
Step 3. Bake the salted brownies in the center of the oven for about 35 minutes, until the edge is set but the center is still a bit soft and a toothpick inserted into the center comes out coated with a little of the batter.
Let the brownies cool at room temperature in the pan for 1 hour, then refrigerate just until they are firm, about 1 more hour.
Lift the brownies from the pan and peel off the waxed paper. Cut the brownies into squares.
Garnish with a little extra MiaBella Fluer De Sel (as the salt on top of the batter will have melted in a bit) & serve!