In a saucepan, bring pineapple and sugar to full rolling boil on stove-top; remove from heat.
Stir in box of jello and let cool.
In a separate bowl, whip whipping cream (unflavored – don't worry about adding any sugar because this dish is sweet enough). Fold in sour cream to whipped cream, then add to jello mix and whip until it's completely mixed together.
Line bottom of 9 x 5" loaf pan with wax paper. Gently pour creamy jello mix into prepared pan.
Cover with aluminum foil and freeze for at least 4-6 hours (preferably overnight).
When ready to eat, remove from the freezer and let it sit for 5 minutes.
Slice in half lengthwise, and then into ¾" slices.