1. Preheat the oven to 350°F (175°C).

2. In a saucepan, heat the milk over low heat until warm but not boiling.

3. In a bowl, whisk together brown sugar, flour, and melted butter until smooth.

4. Beat the eggs in a separate bowl, then gradually add the warm milk while stirring continuously.

5. Combine the egg mixture with the brown sugar mixture and mix well.

6. Pour the mixture into a pie crust and bake for 40-45 minutes until set.

7. Let the pie cool before serving.