Katie Lee's Rustic Apple Pie

Ingredients

• 5 medium apples peeled, cored and sliced into 1/8-inch thick slices, about 4 cups
• 1/3 cup plus 3 tablespoons lightly packed dark brown sugar
• 2 tablespoon cornstarch
• 1 tablespoon fresh lemon juice
• 2 teaspoon ground cinnamon
• 1/4 cup old-fashioned rolled oats
• 2 tablespoon all-purpose flour
• 1/4 teaspoon kosher salt
• 3 tablespoon unsalted butter, melted
• 1 9-inch pie crust, homemade or store-bought, rolled to an 11- to 12-inch diameter
• 1 egg, lightly beaten
• 1 tablespoon raw sugar