Grind 1/4 cup of the walnuts to a powder in a food processor. In a small saucepan, melt the butter over moderately low heat. Add the onion; cook until translucent, about 5 minutes. Add the garlic and cook, stirring, 30 seconds longer. Stir in the cloves, cinnamon, cayenne, and 1/4 teaspoon of the salt. Add the flour and stir to combine. Whisk in the broth and simmer until starting to thicken, about 3 minutes. Add the ground walnuts and simmer 1 minute longer. Remove from the heat and stir in the lemon juice, Parmesan, and parsley.
In a large nonstick frying pan, heat the oil over moderately high heat. Season the turkey with the remaining 1/4 teaspoon salt and the pepper. Cook the turkey cutlets until just done, 1 to 2 minutes per side. Serve with the walnut sauce, sprinkling the additional nuts over the top.
Menu Suggestions: Roasted asparagus and sautéed peppers are vegetables that taste particularly good with both walnuts and Parmesan cheese.
Wine Recommendation: The walnuts will stand up to a bold red wine. Try one from the Northern Rhône in France or a California cabernet sauvignon.