1. In large bowl, combine flour, baking powder, and 1 teaspoon salt. With pastry blender or 2 knives used scissors fashion, cut in shortening to resemble coarse crumbs. Add milk, stirring until dough holds together; turn onto floured surface and knead until smooth and elastic, about 3 minutes.
2. On lightly floured surface, with floured rolling pin, roll half of dough into 12" by 9" rectangle (set remaining dough aside). Cut rectangle into twelve 3" by 3" squares. Repeat with the remaining dough.
3. Into 1-quart saucepan, drain juice from crushed pineapple; set aside. In 2-quart saucepan over low heat, heat crushed pineapple; keep warm.
4. In 3-quart saucepan over medium heat, heat 1 1/2 inches salad oil to 350°F. on deep-fat thermometer (or heat oil in deep-fat fryer set at 350°F.). Fry 2 dough squares at a time in hot oil, turning with slotted spoon as soon as they rise to the surface and turning often until both sides are golden brown (dough will puff up). Remove puffs to paper towels to drain. While puffs are still warm, with small knife, carefully open each puff at one side; fill with 2 tablespoons crushed pineapple; keep warm. (Puffs should be filled immediately; they become too crisp and will break when cool.)
5. Into pineapple juice, stir cornstarch, cinnamon, and 1/4 teaspoon salt. Cook over medium heat, stirring constantly, until mixture thickens and boils; boil 1 minute.