Preheat oven to 160°C (320°F)
In a large bowl, mix together the yogurt, light butter, vanilla extract, and almond milk. Microwave the mixture for 30-40 seconds
Add the cocoa powder to the mixture and mix well. The cocoa powder will bloom, giving the cake its rich chocolate flavour
Add the egg and granulated sweetener to the mixture and whisk until fully incorporated
Sift in the flour, baking soda, and salt, and whisk until a smooth batter forms
Pour the batter into a 20cm × 7cm cake pan lined with baking paper
Bake for 30-35 minutes, or until a toothpick inserted into the center of the cake comes out clean
Let the cake cool completely on a wire rack before frosting
To make the frosting/ganache, melt the sugar-free milk chocolate and mix with the yogurt, cocoa and almond milk. Stir until nice and thick
Spread the frosting evenly over the cake, making sure that the whole cake is covered
Cut the cake into 10 slices and serve. Enjoy your delicious and guilt-free low-calorie chocolate cake!