• Preheat oven to 180°C (350°F). Grease 22x11 cm (8 ½ x 4 ½-inch) loaf pan and line with parchment paper. Set aside.
• In a small bowl, whisk together the flour, cornstarch, cocoa powder, baking soda and salt.
• Using an electric mixer beat the butter and sugars until creamy, 3-4 minutes.
• Add the eggs one at a time, beating well after each addition. Scrape down the sides of the bowl. Add in vanilla.
• With a mixer on low speed, add the dry ingredients in 3 additions alternating with the guinness beer and heavy creamy (dry-wet-dry-wet-dry). Do not over mix.
• Pour the batter into the prepared loaf pan and bake for 45-55 minutes, or until a toothpick inserted comes out clean. If using dark colored loaf pan, start checking at 40 minutes.
• Let the cake cool in the pan for 10 minutes, then remove it gently and set it on a cooling rack to cool completely.

Frosting:

• In a large bowl using an electric mixer beat the cream cheese for 1 minute on high speed until completely smooth and creamy. Beat in the butter until combined. Add the powdered sugar, cocoa powder, vanilla extract, and salt and beat on medium-high speed until combined and creamy. Spread over cooled cake.