To make crust, saute coconut in butter til golden brown. Pour into lightly buttered 10 inch deep dish pie plate and press firmly with back of spoon onto bottom and sides of plate. Chill.
In medium pan, mix sugar, cornstarch and salt. Gradually stir in half and half. Cook and stir over medium heat til mixture comes to a boil and thickens. Boil for 2 minutes and remove from heat. Stir 1/4 cup of mixture in pan into beaten egg yolks, then stir egg mixture into saucepan. Cook 2 more minutes. Stir constantly. Remove from heat and add vanilla. Cool for 10 minutes stirring occasionally. Cover and refrigerate.
Slice bananas and arrange on bottom of crust. Pour cold filling over bananas, refrigerate, covered, at least 2 hours before serving