If the beef stew is frozen, defrost overnight in the fridge first. Transfer to a flameproof casserole and stir through the mustard.
Heat the oven to 200C/180C fan/gas 6. Tip the flour into a large bowl and stir in the cayenne, baking powder and 1 tsp salt. Rub in the butter using your fingertips to combine – it should have a sandy texture. Use a cutlery knife to stir in the cheese and parsley.
Pour in the milk and use the knife to stir it in until the mixture clumps together. If it looks dry, add a little more milk. Tip the dough onto a lightly floured surface and gently knead until any dry floury patches are incorporated – try not to overmix, as you’ll end up with tough scones. Roll or pat the dough until it’s roughly 1cm thick. Use a 5cm cookie cutter to stamp out the scones – we made 18. Arrange the scones on top of the beef stew in a single layer, leaving space for them to expand during cooking. Place any others on a baking tray lined with baking parchment. Sprinkle each with a little more cheese, cover the casserole with a lid and bake for 15 mins along with the extra scones.
Remove the tray of scones from the oven and leave to cool. Uncover the casserole and return it to the oven for another 15 mins, or until the scones on top are puffed and golden. Serve with cooked green veg, if you like.