Cook pasta for 6 minutes. Strain and rinse with cold water.
To soften the butter, put out of fridge a few hours before cooking. Alternatively heat up in microwave for 10-20 secondes. It should be soft but neither hot nor liquid.
Separate the eggwhite and yolk.
Mix butter, egg yolk, salt, pepper and nutmeg until it's creamy. Stir in ham, sour cream, garlic, parsley and pasta. The pasta should not be hot anymore.
In an extra bowl, mix the egg whites until stiff.
Gently "fold in" the stiff eggs to the pasta and ham.
Grease a baking pan with butter and sprinkle with bread crumbs
Pour the mixture into the pan and sprinkle with more breadcrumbs.
Bake in the oven for about 45 minutes on medium heat (~ 150°C / 300°F with circulating air).For the first 20-30 minutes cover the pan (with a lid or aluminum foil) that the crumbs do not burn. Uncover for the last 20 minutes, so the crumbs become crispy. Enjoy!