• Preheat the oven to 325°F. Grease and flour two 4x2 inch round cake pans.
• In a small bowl or custard cup, stir together the cocoa powder and warm coffee or water. Add the half & half and stir until smooth. Set aside.
• Whisk together the flour, baking soda and salt.
• In a mixing bowl, using an electric mixer, beat the sugar and butter until light creamy. Add the egg and beat until light and fluffy, stopping to scrape the sides of thebowl. Beat in the vanilla.
• Add the flour mixture and the chocolate mixture alternately, stirring by hand with a heavy duty scraper, until batter is smooth. You can stir in a tablespoon or so of mini chocolate chips at this point if you'd like to.
• Pour the batter into the two pans, dividing evenly. You should get a little under 6 oz of batter in each pan. Tap to remove air bubbles.
• Bake at 325 degrees F. for about 25 to 30 minutes until the center of a cake springs back a little when touched. Internal temperature should be about 200 F. Let cool in the pans for about 10 minutes, then carefully loosen and turn from pan.

Make Frosting

Frosting

• Put the chopped chocolate and the butter in a mixing bowl, preferably one that is microwave-safe in case you need to heat the chocolate mixture again.
• Microwave or heat the cream in saucepan or microwave-safe measuring cup until it starts to boil, then pour over the chocolate and butter. Let stand for 1 minute, then whisk until chocolate is melted and smooth. If for some reason the chocolate doesn't melt all the way, you can heat it again for 10 seconds. Whisk in Kahlua and vanilla.
• Chill the mixture just until it is cool room temperature. Don't let it get too cold.
• Beat with a hand-held electric mixer for about 30 seconds or just until creamy and smooth.
• Frost the cake.