Cheesy Leek and Spinach Pasta

BBCgoodfood.com recipe that jumped out at me while I was at the Dr's office. Photocopied it and then forgot about it. It comes from a November 2003 (The Dr's wife & I share recipes and she had left the magazine there by mistake.)

• Ready In: 35 mins
• Serves: 4

Ingredients

• 2  tablespoons butter
• 1  tablespoon olive oil
• 2  large leeks, total weight about 1lb, thinly sliced
• 16  ounces  penne rigate or 16  ounces  your favourite pasta
• 6 3⁄4 ounces creme fraiche or 6 3⁄4 ounces sour cream
• 1  tablespoon coarse grain mustard
• 4 3⁄8 ounces danish blue cheese, roughly diced
• 8  sun-dried tomatoes packed in oil, drained and thinly sliced
• 7 7⁄8 ounces  baby spinach leaves
•  salt, to taste
•  fresh coarse ground black pepper, to taste
•  crushed red pepper flakes, to taste (optional)
•  chopped pistachio nut (to garnish)

Directions

1. Melt the butter with the oil in a large pan, put in the leeks and splash in a little hot water.
2. Cover and cook over a low heat, stirring occasionally, for about 10 minutes until no longer squeaky.
3. While the leeks are cooking, boil the penne in salted water according to the packet instructions.
4. Meanwhile, add the creme fraiche and mustard into the leeks, add three-quarters of the cheese and season well.
5. Stir until the cheese melts.
6. Season the leeks mixture with salt and pepper, to taste.
7. Take off the heat.
8. Drain the pasta, reserving the cooking water.
9. Pour the pasta into the sauce and stir, adding enough cooking water to make the sauce coat the pasta.
10. Add crushed red pepper flakes, if using.
11. Stir in the spinach, a big handful at a time, until it wilts, splashing in a little more water if needed.
12. Toss in the remaining cheese and serve.