For the Sweet Potato Crust

• 1 large sweet potato
• 3-3/4 cup all-purpose flour plus more for shaping
• 1-1/2 tsp kosher salt
• 1/2 tsp freshly ground black pepper
• 1/2 lbs (2 sticks) unsalted butter, cut into pieces, chilled
• 1 large egg
• 1/2 cup whole milk
• 2 large eggs beaten with 3 tablespoons cold water

For the Pot Pie Filling

• 4 tbsp (1/2 stick) unsalted butter
• 1 medium yellow onion, finely diced
• 3 cloves garlic, finely chopped
• 1/4 cup all-purpose flour
• 1 quart whole milk, heated, or more if needed
• 3/4 lbs cremini mushrooms, quartered and sauteed in canola oil until golden brown
• 2 potatoes, peeled, cut into medium dice, blanched *see notes on blanching
• 2 carrots, cut into matchsticks, blanched
• 1 cup frozen pearl onions, preferably half red and half white, blanched and drained
• 1 cup frozen peas, blanched and drained
• 1 roasted chicken, shredded 3 lbs
• 2 tsp pureed canned chipotle chile in adobo or 2 teaspoons smoked sweet Spanish paprika
• Kosher salt and freshly ground black pepper
• 1/4 cup coarsely chopped fresh flat-leaf parsley