Place milk (and coconut) into a small pot over medium heat. Bring to simmer.
In a small bowl, stir eggs, egg yolks, sugar, and flour together until combined. Slowly whisk hot milk into the egg mixture. Place hot milk and egg mixture back into the hot pot and bring to boil. Whisk while boiling filling, 2 minutes, or until very thick. Remove from heat and stir in vanilla (and coconut) extract.
Pour into the pie shell. Press plastic wrap directly over the top filling and refrigerate until cold and plastic wrap comes off clean.
To complete tart, top with banana slices. Whisk cream together with powdered sugar and vanilla until stiff peaks form. Spread over pie, ensuring all bananas are covered. Sprinkle with toasted coconut, if desired. Refrigerate until ready to serve.