
1 3/4 cups cake flour
3/4 cup cocoa powder
1 tablespoon ground cinnamon
3/4 teaspoon bicarbonate of soda
1/4 teaspoon baking powder
1/2 teaspoon salt
1 cup unsalted butter, at room temperature
1 1/4 cups granulated sugar
1/2 cup packed dark brown sugar
1 large egg
1 teaspoon pure vanilla extract
For the icing:
1 cup icing sugar
1 egg white