Heat oven to 180C/160C fan/gas 4.
Dry-fry the mince and onion in a large
non-stick frying pan over a high heat.
Stir frequently to break up the mince,
until well browned. Add the mushrooms
and plain flour, followed by the stock and
Worcestershire sauce. Bring to a simmer,
then gently cook for 10 mins.
Meanwhile, to make the cobbles, mix
the self-raising flour and thyme together
in a bowl. Stir in the yogurt with enough
cold water to form a scone-like dough.
On a lightly floured surface, roll out to
the thickness of about 1.5cm and use
a cutter to stamp out 12 x 5cm rounds.
Stir the peas into the mince mixture,
then transfer to a baking dish. Randomly
place the cobbles on top of the mince,
then bake for 20-25 mins, until cobbles
are risen and golden brown. This is good
served with horseradish sauce.