Preheat the oven to 350 degrees.  Use baking spray to grease and flour a 9×5-inch loaf pan. Set aside.

In the bowl of a stand mixer, combine the brown sugar and butter. Beat until fluffy and creamy.

Beat in the eggs, one at a time.

Add the vanilla and bourbon, and beat into the mixture.

In a medium bowl, whisk together the cake flour, baking powder, and salt.

Gradually add the flour mixture to the butter mixture until they are just mixed. Scrape down the sides and fold into the batter. Don’t over mix at this point or you will have a tough cake.

Spoon the batter into the prepared pan.

Bake in the preheated oven for 1 hour or until a toothpick inserted into the center comes out clean.

Remove the pan from the oven and set the pan on a wire cooling rack.

When the cake is cool enough to handle, invert the cake onto the rack and cool completely.

Meanwhile, make the salted caramel sauce.

In a medium saucepan over low heat, combine the brown sugar, cream, and butter. Stir until the butter has melted into the sugar and cream.

Increase the heat to medium-high and bring the mixture to a boil.

Whisking constantly, boil the mixture for 1 ½ minutes.

Remove the pan from the heat and continue to whisk vigorously for another minute.

Stir in the fleur de sel.  

Allow the mixture to cool to room temperature.

Serve the pound cake with the salted caramel sauce and whipped cream, if desired.