In a medium saucepan, combine sugar and cornstarch. Add half-and-half and egg yolks, whisking to combine. Bring to a boil over medium-high heat; cook for
minute, whisking constantly. Remove from heat, and gradually whisk in butter. Stir in sour cream and vanilla. Let cool slightly; cover and refrigerate until chilled.
In 4 (1-pint) resealable jars, layer custard mixture, bananas, and vanilla wafers; repeat layers as desired. Seal jars with lids, and refrigerate. When ready to serve, top pudding with sweetened whipped cream.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/picnic-banana-pudding-recipe/