Preheat oven to 350 degrees F. Spray a 12 cup Bundt pan with flour-added cooking spray.
In a mixing bowl, combine the flour, sugar, brown sugar, cocoa powder, salt, baking soda and baking powder and stir well with a spoon, mashing up any lumps of brown sugar.
Make a well in the center and add the eggs, buttermilk, oil and vanilla. Stir well, then stir everything together with a spoon or silicone scraper.
Pour the hot coffee in and stir until mixed, then with a handheld mixer set on medium speed for about 1 1/2 minutes or until well blended.
Pour into pan and bake for 35 to 40 minutes.
Let cool in the pan for about 15 minutes, then carefully turn onto a wire rack set over paper towels.
Prepare Caramel Drizzle. In a small nonstick saucepan, heat butter over medium until slightly melted. Stir in brown sugar and bring mixture to a boil, stirring constantly. Boil, stirring once or twice, for 30 seconds. Turn off heat. Stir in cream, confectioners' sugar, vanilla and salt and stir until smooth. Drizzle a little over the cake. If it sinks in or seems to thin, add another tablespoon of confectioners sugar and stir a little more. Quickly drizzle over the cake while the icing is still soft -- you have to work quickly or it will start to set in the pan.
Put the chocolate chips in a large heavy duty freezer bag (must be freezer -- not regular type) and microwave bag of chips for 30 seconds. Massage the bag a little and push partially melted chips down toward the bottom corner. Microwave for another 10 seconds and repeat until chips are fully melted. Snip a tiny corner off the bottom of the bag and pipe melted chocolate decoratively over caramel-drizzled cake.