Step 1

Preheat your oven to 350°F. Line a 9-inch square cake pan with parchment paper.

Step 2

Sift flour, cocoa, baking powder and baking soda into a large bowl. Add sugar and salt and whisk to blend well.

Step 3

Combine egg, oil, sour cream and vanilla in a medium bowl and whisk to blend until smooth. Pour into the bowl with the dry ingredients and mix with an electric hand mixer on medium-low until blended. It will be thick and somewhat dry. Add the hot coffee gradually in two stages to minimize clumps forming and beat until evenly combined and the batter smooth.

Step 4

Spread batter into prepared pan and bake for 24-27 minutes until the cake springs back when pressed gently and a skewer inserted into the center comes out clean. Transfer pan to a wire rack and let cool for 15 minutes before inverting onto the rack to cool completely.

Step 5

For the frosting, combine cream, honey, salt and chopped dark chocolate in a small saucepan over low heat and stir gently as the chocolate slowly melts. Keep an eye on it and let the chocolate melt slowly, then whisk gently until it is smooth and glossy. Be careful not to over-heat it.

Step 6

Pour it into a bowl and add the sour cream. Stir gently with a whisk until all of the sour cream is incorporated and the mixture is smooth, then place it in the fridge for about 15 minutes to cool but not until it is firm. It should be the consistency of soft pudding. Whisk vigorously for about 20 seconds to lighten it up and use immediately. This frosting will firm up once it cools completely and sets.