Open puff pastry sheet on parchment paper & roll it out into 10 x 10-inch square. Spread the quince paste over the surface then sprinkle with cheese & walnuts.
With a knife, very lightly score a line width-wise across the middle of the pastry. Starting at one side, roll up jelly-roll style, stopping at the score mark in the middle. Starting at the other side, roll up pastry to score mark.
Wrap the roll in the parchment paper & plastic wrap. Refrigerate for at least an hour. Preheat oven to 400 F. Remove roll & slice into 3/8-inch slices (or larger if you prefer). Place cut side up on a lined baking sheet. Bake 12-15 minutes or until golden. Remove to wire racks to cool completely. Store in air-tight container.