Heat oil in large skillet over medium heat, then add the leek and sprinkle with salt and pepper. Cook, stirring until softened about 5 minutes
4
Add mushrooms and cook another 8-10 minutes
5
Add chicken broth and rosemary sprig; bring to a boil and cook for 1-2 minutes. Add carrots and chicken (chopped); reduce heat and simmer 8-10 minutes
6
Add peas and cook another minute. Then take out the rosemary sprig and discard.
7
Put cornstarch in a bowl, then add a couple of tablespoons of the hot broth to make a paste. Add to the skillet and cook for another minute or two, until the broth thickens. Add contents of the skillet to an oven-proof pan.
8
Mix the dry ingredients for the cobbler crust, then cut the butter into the flour mixture. Add the egg and buttermilk and mix until sticky. Drop by spoonfuls onto hot chicken vegetable mix, then smooth to a crust.
Bake in the oven 30-35 minutes (until the crust is done).