With a fork, mix the three egg yolks together in a small cup or bowl. In a second bowl, whisk flour with half of the warm milk, until smooth.
Whisk the egg yolks and the salt into the milk/flour mixture, then whisk in the remaining cup of warm milk. Set aside.
Place the butter in a saucepan and soften it a little over medium heat.
Add the brown sugar and whisk or stir for about 2 minutes or until butter is melted and sugar has dissolved.
Whisk the milk mixture into the saucepan. Continue whisking constantly over medium heat until mixture thickens and bubbles — this should only take 2-3 minutes. After big bubbles start to form, continue whisking for another 2 minutes.
Remove from heat and stir in the vanilla.
Lay a sheet of greased waxed paper directly over the top to prevent a skin from forming and let cool for about half an hour at room temperature.
Transfer to the baked pie shell and chill thoroughly.Shortly before serving, prepare the whipped cream. In a chilled metal bowl using chilled beaters, beat the cream and sugar until stiff peaks start to form. Beat in the vanilla. Pipe around edges of the pie.
