Mix the softened butter, sugar, cinnamon and salt until you have a soft spreadable paste.
Unroll the puff pastry keeping it on the paper it came wrapped in.
Gently spread the filling over the pastry in an even thin layer, leaving a small gap on one end. Brush the edge with a little beaten egg and press to seal.
Roll the pastry, starting from shortest edge, using the paper to help you, into a log.
Slice the log into nine equal pieces using a sharp knife or dental floss (unflavoured!).
Place slightly apart on baking paper (or a reusable liner) and flatten slightly. Brush with the egg wash and sprinkle with pear sugar, if using.
Bake for 20-25 minutes or until the cinnamon swirls are golden.
Mix the ingredients for the glaze together and drizzle over the cinnamon swirls. Serve slightly warm.