Preheat oven to 350 degrees
Pour 3/4 cup of boiling water into a measuring cup and add dried mushrooms. Set aside for about 10-15 minutes to soften.
Slice the light green part of the leek into thin rounds.
Drain the wild mushrooms from their liquid, reserving the liquid, and chop them well.
Heat the tablespoon of oil in a dutch oven on medium high heat, and add leeks, crimini and wild mushrooms, and 1 tablespoon salt.
Sauté vegetables until leeks start to turn golden brown.
While the vegetables are browning, drain the mushroom liquid through a fine sieve or coffee filter, to remove any sandy grit, into a 2 cup measuring cup. Add chicken stock to make a total of 2 cups of broth.
When vegetables are softened and golden, add 3 tablespoons of the new I Can't Believe It's Not Butter spread to the dutch oven.
Reduce heat, and let I Can't Believe It's Not Butter spread melt. Stir well to coat vegetables, and sprinkle flour over all. Stir to coat the vegetables with flour butter mixture, and cook for about 1 minute.
Increase the heat to high. Add mushroom-chicken stock and mix well until stock thickens. Add pepper, and herbs de provence.
Add shredded chicken breast. Bring mixture to a boil, and then reduce heat to a simmer.
Let the mixture cook for about 5 minutes on low heat, until thickened and heated through.
Add milk. Stir well to combine and remove from heat.
Spoon potpie mixture into a 6-cup casserole dish.
Melt the remaining 1 tablespoon of new I Can't Believe It's Not Butter spread in a microwave safe bowl or measuring cup.
Lay 10 sheets of phyllo dough on a flat surface.
Brush the top sheet with I Can't Believe It's Not Butter spread, and crumble sheet like you would crush a piece of paper. Lay on top of the potpie in the casserole dish.
Repeat with the remaining pieces of phyllo dough.
Bake for 15 minutes, or until the phyllo dough is light golden brown.
Let sit for 5-10 minutes before serving.