In a medium saucepan, whisk together 3/4 cup sugar, 1/2 cup flour, and 1/4 teaspoon salt until blended.
Gradually whisk in 2 cups milk until smooth.
Cook the mixture over medium heat, stirring frequently, until it comes to a full boil (bubbly). Continue to cook and stir for 2 minutes.
Remove the pan from the heat. In a small bowl, place the 3 beaten egg yolks and temper them by whisking in a small amount of the hot milk mixture a little at a time until the yolks are warmed. Immediately whisk the tempered yolks back into the saucepan.
Return the saucepan to medium heat and cook, stirring constantly, for 2 minutes until the filling is thickened.
Remove the pan from the heat. Stir in 2 tablespoons butter, 2 teaspoons vanilla, 1 cup flaked coconut, and 3 ounces cream cheese. Stir until the butter and cream cheese are fully incorporated and the filling is smooth.
Pour the filling into 1 cooled baked pie shell. Smooth the top, then chill the pie until the filling is set before serving.