Whisk flour, baking powder and salt. Whisk oil, milk and egg; pour over flour. Stir lightly with your fingers until it just comes together to form fairly smooth dough. If dough is too soft, add extra flour until you reach the desired consistency. It has to be soft, slightly tacky, but not sticky.
Transfer dough onto a piece of plastic wrap. Form into a disc, wrap and refrigerate for at least 30 minutes.
Preheat oven to 425F
Coat a skillet with cooking spray or a little bit of olive oil and heat over medium-high heat. When pan is hot enough, add chicken pieces, sprinkle with salt and pepper and cook for 5 minutes, then turn each piece to cook the other side until nice and golden brown. (You could also use leftover chicken or turkey, in which case you wouldn't need to cook it for so long. You'd only need to worry about browning it slightly)
Add onions, celery, carrots, salt, pepper and nutmeg. Cook until fragrant and onions turn translucent, about 2-3 minutes.
Add chicken stock and water and bring to the boil. Lower heat to medium-low.
In a small mixing bowl, add whole wheat flour, cornstarch and whisk to combine. Add about ½ cup of the cooking liquid and whisk until smooth and well combined and has the consistency of thin pudding. Add more liquid if necessary.
Transfer this mixture back to your skillet and mix with a wooden spoon until well combined. Add peas, bring back to the boil and simmer for about 1 minute. Set aside.
On floured surface, roll out dough to form a 13" inch square. Cut out four 6" inch disks.
Divide chicken mixture between four individual oven safe ramequins or soup bowls.
Top each bowl with a dough disc and pinch the dough around the perimeter to seal the mixture in.
Pierce 4 holes at the top of each pie to allow steam to escape.
Place in the oven and bake for 20 minute, until the crusts are nice and golden.
DON'T THROW AWAY THAT LEFTOVER DOUGH!
Of course, when you try and cut out rounds out of something square, you invariably end up with "scraps". By all means, don't throw them out.
Just roll out your dough to form a roughly 4" x 12" rectangle. Cut that into eight ½" strips.
Take 2 strips at a time and place them one on top of the other, then grab the ends and twist each end in 2 different directions, until you get a nice twisted "straw". Transfer to a non stick baking sheet.
Repeat the process with the remaining strips and bake in a 425F oven for about 12-15 minutes, until crispy and golden.
Take out of the oven and try resisting the urge to eat them all at once!