Cut each defrosted pastry sheet into 12-16 squares (depending on how large you'd like the pastries to be).
Press the pastry squares into the bases of the muffin tin.
Cut the brie cheese into 24 equal sized pieces. Place the pieces of brie into the pastry base.
Top the brie with 1 teaspoon of cranberry sauce or cranberry jelly and a small sprig of rosemary.
Bake the brie and cranberry puff pastry bites for 10 minutes or until the pastry is lightly golden and puffed.