4 russet apples, to serve
4½ tbsp fresh snipped chives
1 tsp English mustard powder
510g/1lb 2oz plain flour, plus extra for flouring
2¼ tsp baking powder
generous pinch salt
65g/2½oz unsalted butter, plus extra for serving
380g/13oz strong cheddar
300ml/10fl oz milk
1 free-range egg, beaten with a little milk for glazing