Heat a skillet over medium high heat. Pour a few glugs of olive oil into preheated pan and sauté leeks until tender and start to caramelize. Season with salt and pepper. Set aside to cool.
Whisk egg whites and cream of tartar until stiff peaks form. Set aside.
Whisk together yolks, heavy cream, ham, asparagus and cooled leeks, and season with salt and pepper.
Fold whipped egg whites into egg mixture.
Heat ebelskiver pan over medium-high heat, add 1 teaspoon of ghee to each cavity and sprinkle lightly with 1/2 teaspoon of Parmesan cheese.
Fill each cavity halfway with prepared 'batter' and sprinkle with grated cheese of choice. Cover with remaining batter, sprinkle with more grated Parmesan, and cook for a minute or two until eggs begin to pull away from the sides. Using skewers, flip over, cooking for another 2-3 minutes until cooked through.
Serve with fresh, chopped parsley if desired, and consume hot.