Preheat the oven to 400F/200C. Cut the cauliflower into florets, carrot into large pieces, pumpkin into 4 inch pieces, onion into quarters. Arrange on a baking sheet, season with salt and dried sage. Scatter unpeeled garlic cloves and drizzle with 2 tbsp of olive oil. Roast for 40 minutes. (You can do this step up to 2 days ahead)
While the vegetables are roasting, prepare the filling. Cook the shallots in olive oil on low heat until soft for 5-7 minutes, add the herbs and cook for 1 minute longer, then add chicken and stock, turn the heat up and bring to a boil, then add cornstarch to thicken it, then add the cream and take it off the heat.
When the vegetables are roasted and cooled, cut them into bite-sized pieces, peel the roasted garlic and mince it. Add the roasted vegetables to the chicken, mix and turn the heat on and bring the mixture to a boil, check for seasoning and add more salt if needed. Your liquid should have the consistency of a gravy. If it’s too runny, add more cornstarch to thicken it.
Divide the chicken and roasted vegetable filling into two deep 8 inch pie plates and let it cool slightly. Then cover with a pie crust, press down with a fork into the rim of your pie plates to seal your pot pies. Brush with a beaten egg and cut little slits in the crust. Bake in a preheated oven at 375F/190C for 30 minutes or until golden and the filling is piping hot.