To make the caramel. Line a baking sheet with parchment paper. In a large pot, cook the sugar over medium heat, stirring occasionally until the sugar has melted and turns a golden caramel, about 8 minutes. Remove the pot from the heat and add the chunks of butter, whisking until combined. Then, stir in the cream. Return the pot to medium heat and cook the mixture, stirring until the caramel has thickened and easily coats the back of your spoon, about 5-8 minutes. Remove from the heat and stir in a pinch of salt. Pour onto the parchment paper. Freeze in the freezer for 20 minutes to harden. Preheat the oven to 350° F. Line a 9x9 inch square pan with parchment paper.In the microwave, melt together the butter and 1 cup chocolate chips (stirring at 30-second intervals) until melted and smooth. Stir in the sugar, coffee powder, Kahlúa, and vanilla. In a small bowl whisk the eggs for 1 minute until bubbly on top. Stir the eggs into the chocolate mix. Add the flour, cocoa powder, baking powder, and salt. Stir until just combined. Stir in the remaining 1/2 cup chocolate chips. Evenly spread half the mixture into the prepared baking pan. Dollop spoonfuls of Nutella over the batter. Spoon the remaining batter over top, using a spoon to lightly smooth out the batter. It's ok if the batter does not cover up all the Nutella. Grab the caramel piece from the freezer and break/cut into pieces. Stick the caramel into the brownies, you may not need all of the caramel. Bake 28-30 minutes or until the brownies are just set. Let cool...or cut and enjoy warm.