Preheat your oven to 350°F (175°C). Grease and flour a 9×13-inch baking pan or line with parchment paper.
Mix the Cake Batter
In a large bowl, combine the cake mix and instant chocolate pudding. Add eggs, brewed coffee, sour cream, oil, and dark rum. Beat on medium speed until smooth and well combined.
Add Chocolate Chips
Gently fold in the chocolate chips, reserving a few for topping if desired.
Bake the Cake
Pour the batter into the prepared pan and smooth the top. Bake for 35–40 minutes, or until a toothpick inserted in the center comes out clean.
Cool & Serve
Let the cake cool in the pan for 10–15 minutes, then transfer to a wire rack or serve directly. Top with reserved chocolate chips, whipped cream, or a dusting of powdered sugar, if desired.
Serving & Storage Tips
