Instructions
1. Mix the flour, mixed spice and a pinch of salt in a small bowl. Using an electric hand whisk, beat the egg white in a clean glass bowl until it forms stiff peaks, then set aside.
2. Put the yogurt, sweetener, carrot, orange zest, vanilla extract and egg yolk in a mixing bowl and mix until well combined. Stir in the flour mixture, then carefully fold in the egg white using a metal spoon.
3. Scrape the mixture into a microwave-safe mug (one that’s around 250ml is ideal – try to avoid anything wide and shallow) and cook on High in a 900W microwave for 2 minutes. Leave to cool in the mug until just warm – it will sink a little as it cools.
4. For the topping, mix the yogurt and sweetener together, then spoon it over the just-warm cake. Top with the extra orange zest and cinnamon to serve.