Preheat your oven to 350oF (180oC). Lightly butter and flour a 21cm square pan. Line the base with baking paper.
In a medium bowl, combine the egg whites, vanilla and red food colouring. Lightly mix together. In a second medium bowl, sift together the dry ingredients and set aside.
In a stand mixer with the paddle attachment, beat together the butter and oil for one minute on medium speed. Add the flour mixture and the buttermilk and mix on low speed to combine. Increase the speed to medium and beat for 1 1/2 minutes, scraping down the sides of the bowl.
Reduce the speed to low and carefully add half of the red egg mixture. Increase the speed to medium and mix for 30 seconds until combined. Reduce the speed again, add remaining egg mixture and mix on medium speed until well combined.
Pour the batter into the prepared pan and smooth the surface. Bake for 30 - 35 minutes or until an inserted skewer comes out clean or the cake springs back when lightly touched.
Allow the cake to cool for 10 minutes and then remove from pan. Completely cool and then cut into thirds and then each strip into thirds to create 9 pieces of cake.
For the frosting, melt the chocolate in the microwave, being careful not to overheat. Set aside to cool until no longer warm to touch.
In a food processor, combine the cream cheese, butter and sour cream until smooth. Add the cooled chocolate and blend until it is incorporated and then pulse in the extract. Refrigerate for 20 minutes.
To assemble, coat each piece of cake with frosting on all sides. Roll in the shredded coconut to completely coat. Refrigerate until serving.