Pre-heat oven to 350°.
In the bowl of a stand mixer, using paddle attachment, cut chilled butter into the flour until small pea-sized pieces form (or use pastry blender or two knives). Slowly add ice water just until dough comes together (not sticky). Add 1 tsp additional water at a time if dough is too dry. Do not over-handle dough.
Divide dough in half if making double recipe. If making single crust, use all of the dough. Roll between sheets of parchment or plastic wrap, to about 1/8" thick. Peel off top layer and invert the dough into lightly greased pie plate. (Cover and chill if dough is too soft.)
Pre-bake the crust in middle of oven for 28 to 30 minutes.
Combine flour, sugar, salt, and milk in a medium saucepan. Simmer on medium heat and stir constantly until thick. Reduce to a low heat and continue to stir for 2 additional minutes.
In a separate small bowl, slightly beat 3 egg yolks, pour a small amount of the hot mixture into egg yolks and combine, then pour the eggs back into the hot mixture. Cook for two minutes longer, stirring constantly. Remove from heat and stir in vanilla.
Fill cooled pie crust with custard, add fresh berries and refrigerate for one hour. Serve and enjoy!
