Prepare the pie crust by placing it in a 9-inch pie dish and pressing it gently against the sides and bottom.
In a large mixing bowl, beat the eggs until light and frothy. Add the whole milk, vanilla extract, and melted butter, mixing until well combined.
In a separate bowl, whisk together the flour, salt, cinnamon, and half a cup of sugar. Gradually add this dry mixture to the egg mixture, stirring gently until just combined.
Fold the cranberries into the custard mixture, ensuring they are evenly distributed.
Pour the custard mixture into the prepared pie crust and bake in a preheated oven at 350°F for 40 to 45 minutes.
Let the pie cool at room temperature for at least 1 hour before slicing.