With another paper towel, dab softened apples to absorb any excess juice. Begin forming a rose by rolling 1 apple slice into a tight spiral. Wrap another slice, always skin side up, around this bud, then repeat with 5 to 6 more slices. If the slices aren't pliable enough, return to the microwave for 30 more seconds.
Place rose on the crumpled paper towel to "set up" and repeat with the remaining apple slices — microwaving, dabbing, wrapping and propping — until you have 9 roses. There will be extra slices, which we'll use in a minute.
Take pastry squares out of the refrigerator and place a rose in the center of each dollop of filling, anchoring firmly. Press remaining slices into filling, curving around the rose to create more petals. You can make tiny rosebuds from smaller slices, placing them so they peek out from under the larger rose. (Consider any remaining apple slices a snack!)
With a pastry brush, carefully brush melted apple jelly over each rose so it glistens, then sprinkle with a pinch of decorative sparkling sugar, if desired.
Place pans in oven for 18 to 20 minutes, or until golden brown, switching pans on racks halfway through the baking time.
Cool on wire racks, and serve warm or at room temperature the same day. If desired, sprinkle with additional powdered sugar before serving.