Preheat oven to 350 degrees.
In a large bowl, beat the butter and sugar together until fluffy. Beat in the eggs, vanilla extract and sour cream.
In a small bowl, combine the espresso powder and hot water. Stir until the espresso powder is dissolved. Beat into the butter mixture until incorporated.
In a separate bowl, whisk the flour, baking powder and salt. Blend into the wet ingredients.
Coat a 9x13 baking pan with nonstick cooking spray, or line with parchment paper. Press the cookie batter into the pan, making sure to press into the corners. Bake 20 minutes.
Stir chocolate chips and coconut oil together in a microwave safe bowl. Melt the chocolate in 30 second increments, stirring in between, until it's smooth and spreadable. Spread the melted chocolate evenly over the cookie layer. Cover and freeze for 1 hour.
Remove from freezer and slice into bars. Drizzle with caramel sauce and sprinkle with sea salt, if desired.