Optional garnishes: 3 green onions, thinly sliced and 1 tablespoon chopped fresh parsley
Preheat oven to 400°F.
In a large (10-inch) cast-iron skillet or nonstick, oven-safe skillet, sauté potatoes in olive oil until just softened.
Add butter to skillet. Sauté diced yellow onion, a teaspoon of kosher salt, and ¼ teaspoon black pepper. Continue to sauté until potatoes and onions are softened, 3-5 minutes.
Add diced corned beef to the vegetables. Cook for 2-3 minutes on one side. Flip after 3 minutes and press into the pan with the back of a spatula.
Pour chicken stock over top of the hash. Season with 1 teaspoon kosher salt and ¼ teaspoon black pepper.
Top with your choice of cooked egg: fried, poached, or over easy. Optional: use a spoon to create a well for a freshly cracked egg, 4-6 wells for 4-6 eggs. Bake in a preheated oven at 400°F for 8-12 minutes, depending on desired doneness for the eggs.
Serve directly from the skillet. Garnish with optional toppings: fresh cracked black pepper, green onion slices and chopped fresh parsley.