Whisk in milk and egg yolks until blended. Bring to a boil over medium heat. Boil, whisking constantly, 16 minutes or until thickened.
Remove from heat; stir in 1/2 cup coconut and 1 teaspoon vanilla.
Arrange banana slices in bottom of baked Pastry; pour custard over banana.
Beat egg whites, cream of tartar, and 1/8 teaspoon salt at high speed with an electric mixer until foamy.
Add 1/3 cup sugar, 1 tablespoon at a time, beating until stiff peaks form and sugar dissolves (2 to 4 minutes). Stir in remaining 1/4 teaspoon vanilla.
Spread meringue over hot filling, sealing to edge of Pastry.