Heat oven to 425°F. Place cereal in large plastic food bag; crush with rolling pin.
Unfold 1 pastry sheet on work surface. Spread with 2 tablespoons jam. Sprinkle with half of crushed cereal. Roll in from two opposite sides until sides meet in center. With a serrated knife, cut crosswise into 1/2-inch-thick slices. Place cut side down on ungreased baking sheet. Sprinkle with 1 tablespoon sugar.
Bake in 425°F oven until golden, about 15 minutes. With spatula, remove to rack to cool. Repeat with remaining pastry, jam, cereal, sugar. Serve warm or at room temperature. Store in airtight container at room temperature for up to 1 week.