Preheat oven to 350 degrees F. Line a baking sheet with parchment paper.
Make the pie dough. Combine 1 ¼ cup all-purpose flour with ¼ teaspoon salt and ½ cup cold butter. Use a pastry cutter to incorporate the butter into the flour until the mixture resembles coarse sand. Add 2-3 tablespoon ice water just until the dough comes together. Shape the dough into a disc and wrap it in plastic wrap. Chill in the fridge until ready to use.
Combine ¼ cup maple syrup with vanilla bean paste in a small saucepot. Simmer over low heat for 5 minutes and remove from heat. Set aside.
Cream together 6 ounces softened cream cheese with ½ cup sugar, 1 egg yolk, and 1 teaspoon vanilla extract until smooth.
Peel and slice the sweet potato into ⅛ inch thick slices. Toss the sweet potato with ⅓ cup melted butter, 1 teaspoon cinnamon, and 2 tablespoon brown sugar.
Dust a clean work counter with flour and roll out the pie dough into a rough circle until it's about ¼ inch thick. Transfer the dough onto the prepared baking sheet. Spread the cream cheese filling in the center, leaving a 1-inch border. Arrange the sweet potato on top of the cream cheese filling, slightly overlapping the slices. Drizzle 2 tablespoon of the vanilla maple syrup over the filling. Fold over the edges slightly over the filling.
Whisk together 1 egg yolk with 1 tablespoon water. Brush the edges of the crust with the egg wash. Bake in the oven for 45-50 minutes or until golden brown. Remove from heat and drizzle extra vanilla maple syrup on top. Serve while warm.