Put the tuna in a food processor, or blender, together with the anchovies, 1 cup of the olive oil, and the flat leaf parsley. Process until the sauce is very smooth. Spoon the crème fraiche into the food processor or blender and process again for a few seconds to blend thoroughly. Season with salt and pepper.

Bring a large pan of lightly salted water to a boil. Add the spaghetti and the remaining olive oil and cook for 8-10 minutes until al dente. Drain the spaghetti, return to the pan and place over medium heat. Add butter and toss well to coat. Spoon in the sauce and quickly toss the spaghetti using forks.

Remove the pan from the heat and divide the spaghetti among 4 ways on individual serving plates. Garnish with the olives and serve at once with the crusty bread.

COOK'S TIP:
If desired, you could add 1-2 garlic cloves to the sauce, substitute ½ a cup of chopped fresh basil for half the parsley and garnish with Unico capers instead of black olives.