Bring a large pot of water to a boil. Then, boil the peeled potato until fork tender. Mash as you normally would, adding butter and milk as needed to smoothen the potatoes. Season with salt and pepper to taste.

In a deep pan, melt 15g of the unsalted butter, then add the garlic. Once the garlic is fragrant, lay down the fish filet. Let one side cook until lightly browned, about 3 minutes, and flip. Let the other side cook for about 3 minutes as well, then remove the fish from the pan and set aside for now.

Using the same pan we cooked the fish in, add the remaining butter and let melt. If your pan still has a lot of butter after cooking the fish, you may omit the extra butter. Once the butter is melted, add the flour and cook until the roux is lightly golden brown.

Add the cold milk to the roux in increments, mixing after each addition. Use a whisk to beat out any lumps. Season with salt and pepper to taste and the hondashi powder. You want a pretty thick sauce, so cook until thickened then set aside for now.

In a small frying pan, heat the oil. Once hot, add the onions and allow them to caramelize. Next, add the peas and carrots. Lightly stir fry until the carrots have just started to soften, then remove from heat.

Add the fish and the stir fried vegetables to the bechamel sauce we made in step 3 and mix together, breaking apart the fish as you do so.

Oil the inside of a small pie pan, then lay down a layer of the mashed potatoes. The layer should be as thick as about half the height of the pan. Next, lay down a layer of the fish and sauce mixture until it’s slightly under the total height of the pan. Spread a layer of mozzarella cheese evenly across the surface.

Using a rolling pin, lightly roll the pie sheet to soften it. Lay one sheet over the pie pan and cut off the excess, leaving about a centimeter around the circumference. Roll the other pie sheet to soften it as well, then cut three strips about 3cm wide. Use the remaining pie sheet to cut out the fish designs or other design of your choice.

Mix together the egg and milk to create the egg wash, then brush it over the surface of the pie evenly. Lay down the three strips and cut it to size to fit the pan. Next, fold over the excess pie sheet and crimp the edges to create the crust design.

Brush the strips with the egg wash and begin to lay down the pieces you cut for your design. Your steps may vary depending on what design you choose to make, but regardless, you must brush the surface of each new layer to ensure the pieces stick together.

Once your design is complete, brush over the entire pie with the egg wash. Place three olives at the bottom and three olives at the top of the surface of the pie.

Bake the pie at 200°C/390°F for 15 minutes, then lower the temperature to 180°C/355°F and bake for 30 minutes or until golden brown. Let the sea-bass pie cool down slightly before serving, and the sea-bass pie is done! 完成です！