Preheat the oven to 400 degrees.
Melt butter in a skillet. Add leeks and carrots and cook until soft (approximately 6 minutes).
Sprinkle with flour. Cook while stirring constantly for 1 minute.
Stir in the stock and bring to a simmer. Stir until it thickens (1-2 minutes).
Stir in the chicken, corn, dijon, and spices.
Remove from the heat.
Cover with a pie crust and brush with an egg mixed with 1 tbsp. water. (The egg wash is optional. It is to brown the crust.)
Bake at 400 degrees for 20 minutes.
Let sit for 10 min and serve!