Place flour, sugar, and salt in a food processor and pulse them for a few seconds to combine. Add the cubed butter and pulse for 10 seconds, or until it is marbled.
Beat the egg into the milk in a small bowl and add to the food processor in batches, pulsing each for about 10 seconds. If you pinch the dough and it is still crumbly, then you need to add about another tbsp. of liquid.
Remove the dough and flatten it into a disc a few inches thick. Wrap in plastic and let it rest in the fridge 30 minutes.
Once ready, place the dough onto a floured tabletop and roll out to ½-inch thickness.
Place the dough into a 12-inch baking pan and gently work it onto and over the sides. Cut the dough accordingly to fit the shape of the pan. Poke holes into the base of the dough with a fork.
Wrap the beans in foil to use as pie weights. Place the wrapped beans onto the dough, making sure they reach the sides of the pan. Bake the shell at 350°F for 20 minutes, then remove the beans and cook another 20 minutes. Remove and let the shell rest until it reaches room temperature. Keep the oven heated to 350°F.
Meanwhile, make the filling. Place all the ingredients into a bowl and whisk together until thoroughly combined.
As soon as your shell cools, place the filing into it and bake 45 minutes or until the middle of the pie looks set. Remove and let rest for at least 1 hour.