2) In a small saucepan, heat the chicken stock and add the bouillon cubes, stirring until dissolved. in a large pan or dutch oven, melt the butter and saute the onions over medium-low heat for 10 to 15 minutes, until translucent.
3) Add the plain flour and cook over a low heat, stirring constantly, for 2 minutes. Add the hot chicken stock to the sauce. Simmer over a low heat for 1 more minute, stirring, until thick. Add 2 tsp salt, 1/2 tsp pepper and the double cream. Add the cubed chicken, carrots, peas, onions, and parsley. Mix well.
4) Place the stew in a 25 x 33 x 5cm oval or rectangular baking dish. Place the baking dish on a sheet pan lined with parchment or greaseproof paper. Bake for 15 minutes.
5) Meanwhile, make the scones. Combine the plain flour, baking powder, salt and granulated sugar in the bowl of an electric mixer fitted with the paddle attachment. Add the butter and mix on low speed until the butter is the size of peas. Add the single cream and combine on low speed. Mix in the parsley.
6) Dump the dough out on a well-plain floured board and, with a rolling pin, roll out to 1cm thick. Cut out twelve circles with a 6cm round cutter. Remove the stew from the oven and arrange the biscuits on top of the filling. Brush them with egg wash, and return the dish to the oven. Bake for another 20 to 30 minutes, until the biscuits are brown and the stew is bubbly.
Note: To make in advance, refrigerate the chicken stew and biscuits separately. Bake the stew for 25 minutes, then place the biscuits on top, and bake for another 30 minutes, until done.