Preheat the fan oven to 340° F (170° C).
Place the flour in a large mixing bowl and add the softened butter, baking powder, icing sugar, yogurt, and lemon zest.
Mix them with your fingertips gently until combined.
Return the mixture to a worktop and form a nice soft dough.
Roll the dough into a log and cut it into 5 equal pieces (approximately 5 oz (140 grams) each) and turn them into balls.
Lightly flour the worktop, sprinkle some flour on a dough ball, and roll it out into an 8" (20 cm) dia circle (approximately ⅕" (½ cm) thick).
Cut the circle into 8 equal triangles and place a teaspoon of apple filling on the wide side of each triangle.
Roll them up into a log shape and place them on a baking paper-lined tray.
Bake for 20 minutes, until lightly browned.
Sprinkle some icing sugar on top when they are still warm.