In the US self raising flour contains ½ teaspoon less baking powder per cup than UK self-raising flour. If you are based in the US use plain or all-purpose flour instead and add 2tsp baking powder.
If the caramel sauce is a little stiff after being stored in the fridge place it in the microwave for 20 seconds to loosen it up and make it easier to spoon into the muffin cases.
Serving: 1 muffin | Calories: 343kcal | Carbohydrates: 51g | Protein: 5g | Fat: 14g | Saturated Fat: 8g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 4g | Trans Fat: 0.5g | Cholesterol: 60mg | Sodium: 254mg | Potassium: 89mg | Fiber: 1g | Sugar: 26g | Vitamin A: 434IU | Vitamin C: 0.1mg | Calcium: 41mg | Iron: 1mg