Prepare and bake pie shell according to package directions for a baked pie shell. Set aside to cool.
Whisk egg yolks, sugar and flour in a medium bowl.
Heat milk and vanilla in saucepan until almost boiling. Remove from heat; add to egg mixture, 1/4 cup (50 mL) at a time whisking continuously, until all of milk has been added. Return custard to saucepan and cook over medium-low heat, whisking continuously, until custard has thickened to a consistency similar to pudding (5-7 minutes). Place plastic wrap directly onto surface of custard (this prevents a 'skin' from forming). Set aside to cool completely.
Spoon cold custard into baked pie shell and top with sliced fruit.
Serve the same day of making. Refrigerate any leftovers.