Preheat oven to 350°F (177°C) and prepare four 8-inch round cake pans by greasing them with unsalted butter and dusting with flour.

In a bowl, sift together flour, cocoa powder, baking soda, baking powder, and salt. In another bowl, cream butter and sugar until light and fluffy. Add eggs, sour cream, and coffee, mixing well. Gradually add dry ingredients until smooth.

Divide batter among the prepared pans, smoothing the tops. Bake for 20-25 minutes, or until a toothpick comes out clean.

Let cakes cool in pans for about 10 minutes before inverting them onto a wire rack to cool completely.

In a medium saucepan, melt sugar over medium heat, stirring constantly until golden. Add butter and cream, stirring until smooth. Fold in toasted pecans and let cool.

Beat softened butter until creamy. Gradually add powdered sugar and mix until fluffy. Drizzle in cooled caramel sauce and mix until smooth.

Layer one chocolate cake on a serving plate, spread buttercream, and drizzle with caramel sauce. Repeat with remaining layers.

To make ganache, heat cream until simmering, pour over chocolate chips, and stir until smooth. Pipe or spoon ganache drips around the cake sides.

Sprinkle chopped pecans on top for decoration. Serve and enjoy!