Berry cupcakes:

1. Preheat oven to 180ºC. Line a 12-hole muffin tin with 10 patty pan cases.
2. In a large bowl, combine flour, cornflour and baking powder.
3. In a separate bowl, add softened butter and sweetener. Beat with a mixer for approximately five minutes until pale and creamy. Add milk, eggs, vanilla and berry compote. Whisk together.
4. Pour dry ingredients into the wet and stir gently until the batter is smooth. 
5. Divide batter into patty pans. Cook for 30 minutes or until an inserted skewer comes out clean. 
6. Once baked, allow to cool in the tin for five minutes before placing on to a cooling rack. Allow cupcakes to cool completely before icing. 

Buttercream:

1. Heat a saucepan filled with a little water over a medium heat. Place a bowl over the top with egg whites and sweetener. Whisk gently until sweetener has completely dissolved.
2. Remove bowl from heat and place on to a stand mixer. Whisk until egg whites are large and fluffy, approximately eight minutes.
3. Turn the mixer to low speed and gently beat in butter, a cube at a time. Buttercream should be smooth and silky. Add in berry compote and food colouring, and mix well until completely combined. 
4. Place buttercream into piping back and pipe on to cooled cupcakes. Top with fresh berries to serve.