Directions:

• Step 1: Preheat your oven to 350°F (175°C). Grease and flour your 9-inch round cake pan, or line it with parchment paper for easy removal.
• Step 2: In a medium mixing bowl, whisk together the all-purpose flour, cocoa powder, baking soda, salt, ground cinnamon, and espresso powder. Set aside.
• Step 3: In a large mixing bowl, using an electric mixer, cream the unsalted butter and granulated sugar together until light and fluffy, about 3-4 minutes.
• Step 4: Beat in the eggs one at a time, ensuring each is well incorporated. Then, mix in the mashed bananas and vanilla extract until combined.
• Step 5: Gradually add the dry ingredients to the wet mixture, alternating with the sour cream. Start and end with the dry ingredients. Mix until just combined; do not overmix.
• Step 6: Gently fold in the chocolate chips until evenly distributed throughout the batter.
• Step 7: Pour the batter into the prepared cake pan and smooth the top. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Allow the cake to cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely.
• Step 8: In a double boiler or microwave-safe bowl, heat the chopped semi-sweet chocolate and heavy cream until melted and smooth. Stir in the espresso powder and mix well. Add the pieces of unsalted butter and stir until incorporated. Allow the frosting to cool slightly before spreading on the cake.
• Step 9: Once the cake has cooled completely, spread the espresso fudge frosting generously on top and around the sides of the cake. Decorate with additional chocolate shavings or chocolate chips if desired.