Heat oil in a fry pan. Add the leek and cook until softened
Add the ham, thyme, cranberries, cream and mustard and cook for a further 4 minutes or until cream has thickened slightly. Remove from heat and set aside to let cool
Meanwhile, cut each pastry sheet into 4 squares. Place 2 tbls of cooled ham mix onto each square
Moisten the edges of the pastry with a bit of water and roll filling into pastry creating a cigar shape placing the seam side down. Using a fork, crimp the edges of the cigar shape, ensuring a tight seal
Arrange pockets on a baking paper lined tray. Brush each pocket with the melted butter and a sprinkle of poppy seeds. Place in an 200°C oven for 15-20 minutes or until pastry is golden brown