1. In a large sauté or frying pan, melt butter and lightly sauté onions until just soft, add spinach and walnuts and toss together to combine and the spinach just soften.
2. Allow to cool then add Castello® Extra Creamy Danish Blue Cheese. Meanwhile preheat oven to 220ºC/425ºF.
3. Season the spinach mixture and bind lightly together using a spatula or fork.
4. Unroll pastry sheet and cut in half along it’s length.
5. Place half the spinach and cheese mixture down one pastry strip, putting it off centre but leaving a border of approx. 1cm/½”.
6. Brush border with beaten egg or milk, then fold over the pastry to cover filling.
7. Press edges together firmly to seal and cut into six equal portions.
8. Repeat with remaining filling and pastry.
9. Place rolls on a baking sheet, brush tops with beaten egg to glaze and bake for 10 – 12 minutes or until pastry is risen and golden.