Add the potatoes to a large pot and fill with cold water and a generous sprinkling of salt. Place over a medium-high flame and partially cover. Cook for about 20 to 25 minutes, reducing the heat if necessary, or until the potatoes fall easily crumble when poked with a fork. Drain the water and return the potatoes to the pot. Add the butter, cream, and milk and sprinkle with garlic salt. Using a hand mixer or potato mashers, blend the potatoes until smooth. Taste and add additional seasoning as desired. Set aside.

Add the milk, bay leaves, and thyme sprigs to a large cast iron pan and lightly season with salt and pepper. Add the fish and scallops, evenly spreading them amongst the pan. Turn the flame to medium and cook for 10 minutes, reducing the heat slightly if it starts to boil to hard. Carefully remove the fish and scallops to a cutting board. Strain the milk through a fine mesh colander into a large bowl. Discard the thyme and bay leaves. Set aside. When the fish is cool enough to handle, flake into bite size pieces. Cut the scallops into quarters.

Preheat the oven to 400°F

Return the cast iron pan to a medium flame and add the bacon. Stirring frequently, cook until the bacon has just turn crispy. Remove and drain on paper towels. Drain off any excess fat, if necessary, leaving about 2 to 3 tablespoons of fat. Add the onions and lightly sprinkle with salt. Cook, stirring often, until just starting to soften ~ about 6 minutes. Add the leeks, scallions, and garlic, cooking an additional 2 to 3 minutes. Sprinkle the flour over the top and stir to fully saturate. Take the milk used for cooking the fish and slowly add to the mixture, stirring constantly until fully incorporated. Add the chives, lemon zest and juice, and fresh dill. Return the fish and scallops to the pan. Stir to combine, season to taste with salt and pepper, if desired, and remove the pan from the heat.

Take the mashed potatoes and dollop them over the the fish filling. Carefully spread the potatoes over the top. If desired, use a fork to fluff up the potatoes. Place the pan in the oven and cook 30 to 40 minutes, or until bubbling and lightly golden on top ~ you can place the cast iron pan under a broiler for a few minutes to create a darker golden brown on the potatoes, if desired.

Remove from the oven and serve. Enjoy!