Mix sugar and flour, add juice from can of pineapple. Mix well. Cook on low to medium heat until the mixture is thick and has a slightly clear look, stirring continuously. When cooked to desired thickness, set aside and cool somewhat.
Peel bananas and slice. Add the pineapple and nuts.
When the mixture of the sauce has cooled a bit, add cream or half-and-half and mix well. Fold the sauce into the fruit mixture and refrigerate. (I have used 2% milk when I didn't have the cream or half-and-half.)