Begin by dicing 2 medium Yukon Gold potatoes and 1 large yellow onion, setting them aside. Soak the potatoes in cold water for about 15 minutes to prevent browning.

In a large pot, melt 2 tablespoons of unsalted butter over medium heat. Add diced onion and 1 bay leaf, stirring occasionally for 5-7 minutes until the onion turns translucent.

Drain the potatoes and add them to the pot. Add enough cold water to cover the potatoes and bring the mixture to a gentle boil. Cook for approximately 10 minutes until fork-tender.

Carefully place 1 pound of fresh haddock or cod on top of the cooked potatoes. Pour in 1 can of evaporated milk and 1 cup of half-and-half, then cover the pot and simmer for about 15 minutes.

Once the fish is fully cooked and the potatoes are soft, remove the bay leaf and stir in the remaining 2 tablespoons of butter along with kosher salt and pepper to taste. Serve hot, garnished with fresh chives.