Wash potatoes, pat dry and rub skins with olive oil

Bake at 425 degrees F for 40-50 minutes, depending on the size of your spud

Let potatoes cool completely, then wrap in foil and refrigerate overnight (just make extra for dinner the night before you assemble your casserole)

Grease a 9x13 baking dish and set aside

Slice baked potatoes into ¼" slices and remove the peel, they should peel easily after being chilled overnight

Whisk the milk, half & half, parsley, onion powder, garlic powder, paprika and whole eggs in a large bowl until mixed, now prepare the Hollandaise sauce

Whisk egg yolks and lemon juice briskly in a stainless steel bowl until thickened and doubled in volume

Place yolk mixture in a double boiler over simmering water and continue to whisk rapidly until mixture thickens

Slowly drizzle in melted butter while continuing to whisk until sauce is doubled in volume

Remove from heat and stir in dijon and cayenne pepper

Add Hollandaise to milk mixture and whisk well until combined

Place a layer of potatoes in the bottom of your greased baking dish, then add a layer of chopped ham, bacon, cheese and chives, if using

Pour half of the milk mixture on top of first layer

Repeat with one more layer and pour remaining milk mixture on top

Cover with foil and refrigerate overnight

Bake at 350 degrees F, uncovered, for 45-50 minutes until edges are golden brown and casserole is set

Allow casserole to sit for for a few minutes before slicing and serving