Preheat the oven to 190°c (170 fan/ Gas 5) and place 12 muffin cases in a 12 hole muffin tin.
Put the caster sugar, plain flour, bicarbonate of soda and 1 teaspoon ground cinnamon in a large mixing bowl.
140 g Caster Sugar, 200 g Plain Flour, 1 teaspoon Bicarbonate of Soda, 1 teaspoon Ground Cinnamon
Whisk together the cooled melted butter, yogurt and eggs in a bowl or jug then gently fold into the dry ingredients.
100 ml Plain Natural Yogurt, 140 g Unsalted Butter, 2 Eggs
Fold in the chopped apple pieces and spoon into the 12 muffin cases.
2 Bramley Apples
Bake in the oven for 16-18 minutes until golden.
For the topping: Mix together the cinnamon and granulated sugar in a bowl. Whilst the muffins are still warm, brush the tops with melted butter, then roll in cinnamon sugar. Allow to cool slightly before serving.
50 g Butter, 50 g Granulated Sugar, 3 tablespoon Ground Cinnamon