Preheat your oven to 375F.
Use a whisk to combine the butter and the ⅔ cup sugar in a bowl.
Add the egg and whisk again.
Using a wooden spoon, mix in the all purpose flour, baking powder, and vanilla.
Spray a 9” glass pie pan with nonstick spray. Use a spatula to spread the pie crust over the bottom of the pan and up the sides as well! Make sure the pie crust goes up the side of the pie pan so that it can hold the custard.
For the filling, use a whisk to combine all of the filling ingredients together except the blueberries. Then, use a spatula or a wooden spoon to mix ½ cup of blueberries into the filling.
Sprinkle the remaining one cup of blueberries over the crust, then pour in the filling mixture.
Bake for 30-35 minutes or until the crust is brown and the custard is mostly set (it will firm up in the fridge!). Enjoy!