Preheat the oven to 400 degrees Fahrenheit .
Start by melting 4 tablespoons of butter in a saucepan over medium heat.
Once melted, add 1 cup of milk and stir until it is warm but not boiling.
Whisk 3 large eggs into the bowl and mix until well incorporated.
In a bowl, combine 1 cup of sugar, 1 ½ tablespoon of vanilla extract, ¼ tablespoon of ground nutmeg, 1 ½ tablespoon of all-purpose flour and mix until combined.
Gradually add the warm milk mixture to the bowl with dry ingredients and whisk until completely blended together.
Grease a 9-inch pie plate with 1/2 tablespoon of unsalted butter and set aside.
In a separate bowl, combine 1/4 cup of sugar, ½ tablespoon of salt and 1¼ cups of flour and mix until combined.
Cut in the remaining 1/2 cup of butter with a pastry cutter or your fingertips until it resembles coarse crumbles.
Sprinkle the butter and flour mixture into the greased pie plate. Using your hands or a spatula, press it evenly until it covers the bottom and sides of the pan.
Pour in the egg custard mixture from earlier and spread it evenly over the top with a spatula.
Bake for 45 minutes or until it is golden brown on top and set.