Prepare pie crust and place in a 9-inch pie plate; be sure to chill the crust at least 30 minutes before filling and baking.

Preheat oven to 350°F.

Stir together brown sugar and cinnamon. Set aside.

Whisk flour, baking powder and salt in a small bowl. Set aside.

Stir melted butter with sugar in a large bowl. Stir in egg and vanilla. Add flour mixture and ½ cup milk into the butter mixture and stir until smooth.

Place half of batter into the prepared pie crust. Sprinkle with brown sugar mixture. Top with remaining batter.

Place pie on a cookie sheet and cover edges with a pie crust shield. Bake until a toothpick comes out clean from the center of the pie, about 42-45 minutes.

As soon as you remove the pie from the oven, whisk the powdered sugar with vanilla and 1 teaspoon milk in a small bowl. Spread over top of the pie to glaze. Let pie cool completely before cutting and serving.