3/4 pound bacon, cut crosswise into 1/2-inch-wide strips, use the good stuff here I use jowl bacon when I can find it & make sure it's thick sliced.
1 1 1/2- to 1 3/4-pound cabbage, quartered, thinly sliced
1 large leek (white and pale green parts only), thinly sliced, wash it well to get out all the sand
3/4 cup water
1/4 cup chopped fresh parsley
1/4 cup chopped green onions
3 tablespoons butter
1 1/2 cups panko
Preheat oven to 375°F. Place bacon in heavy large pot over medium-high heat. Cook until fat begins to render and bacon begins to brown, about 12 minutes you want it browned but not too crisy. Add cabbage and leek. Sauté until cabbage wilts, about 10 minutes. Add water; bring to boil. Cover pot, reduce heat to medium and simmer until cabbage is tender, about 15 minutes. Uncover, increase heat and boil until all liquid evaporates, stirring often, about 10 minutes. Mix in parsley and green onions. Season with salt and pepper. Transfer to 9-inch deep dish pie dish.
At this point you can put the dish in the refrigerator for a few hours & just before serving add the crispy topping.
Melt butter, I just use the microwave. Add panko & stir to make sure it's all coated. Sprinkle panko over cabbage mixture. Bake until heated through, about 10 minutes.