Custard toast

Name: Custard toast
Prep time: 10 min
Cook time: 10 min
Total time: 20 min
Cuisine: European, British
Ingredients: 4 slices Co-op farmhouse white bread; 1 Co-op British free range egg; 125g Co-op 0% Greek style natural yogurt; 1 tbsp Fairtrade icing sugar, plus extra to dust; 1 tsp orange zest, or a few drops vanilla extract (optional); 60g Co-op blueberries; 75g Co-op raspberries