Peel and slice the apples thinly, and put them in a bowl of cold water with a little lemon juice to stop them going brown. Melt the butter in a small saucepan over a low heat and keep warm.
Carefully cut the filo pasty into 30 x 50cm sheets with a knife. Mix the pecans, cinnamon and dark muscovado sugar together.
Lay the first sheet of filo pasty on a clean tea towel on your work surface and brush with melted butter. Sprinkle over a third of the pecan mixture. Lay another sheet of filo pastry on top, brush with butter and sprinkle again with a third of the pecan mixture. Repeat with the third sheet and top everything with the fourth sheet.
Drain your apples well and toss with the caster sugar and drained cranberries. Spread them out along one edge of the top sheet of filo pastry. Brush the opposite edge with a little water. Starting at the edge with the apple mixture on, gently lift the edge of the tea towel and use it to help you roll the pastry up lengthways like a Swiss roll – the apples will end up at the centre. Once it’s all rolled up, press your strudel together gently.
Place it on a baking try and bake in the preheated oven for about 20 minutes or until golden brown. Serve with some good vanilla ice cream.
Try making the strudel with a little ground ginger and cloves for a lovely twist.