Thaw puff pastry at room temperature for 30 minutes. Preheat oven to 400°F.
In a small bowl mix sugar, flour and cinnamon. In another small bowl mix pears, lemon juice and zest. Carefully unfold pastry onto a lightly-floured surface. Roll into 10 x 15-inch rectangle. Brush lightly with water.
Combine sugar-flour and pear-lemon juice mixtures from the 2 small bowls. Spoon filling on pastry and spread to within 2 inches of the short sides and to the edge of the long sides. Starting at the short side, roll like a jelly roll. Cut roll into 8 (about 1-1/2-inch) slices. Place 2 inches apart on baking sheet.
Bake 20 minutes or until golden. Remove from oven and place a Havarti slice on each pastry. Return to oven just until cheese melts, about a minute. Remove rolls from baking sheet and cool on wire rack.