Step 1

Gather all the ingredients. Start boiling 4 quarts (16 cups, 3.8 L) water in a large pot. When the water boils, keep it covered and on low heat until you're ready to cook the pasta.

Step 2

Mince the onion.

Step 3

Remove the core of napa cabbage and cut into 1 inch (2.5 cm) square pieces.

Step 4

Discard the bottom of mushrooms and slice them.

Step 5

Cut the bacon into ½ inch (1.3 cm) pieces. Grate the cheese if your cheese is not shredded.

Step 6

In a large (oven-safe) skillet (I use Le Creuset cast iron braiser), heat the butter on medium heat. Add the bacon, stir to separate, and cook till crisp on the edges.

Step 7

Add the onion and stir to coat well with butter/bacon fat. When the onion is being cooked, start cooking pasta (go to the next step and come back). Continue to saute the onion until tender and translucent, scraping the bottom of the skillet with the wooden spatula.

Step 8

To Cook Pasta: The water in the pot should be boiling by now. If you kept it on low heat, bring it back to medium-high heat. Add 1 ½ Tbsp salt and pasta, stirring to make sure the pasta doesn’t stick to each other. Tip: I usually reduce the cooking time by 1 minute if I have to continue cooking the pasta afterward. Drain if you finish cooking the pasta first, but you should be able to cook the rest of the ingredients in 10 minutes while the pasta is being cooked.

Step 9

When the onion is tender, lower the heat and add the flour. Using the wooden spoon, quickly mix the flour with the rest of the ingredients, scraping off the bottom of the skillet, for 2 minutes. It's important to "cook" the flour to rid the raw flour taste. Then gradually add milk, 2 Tbsp at a time, while stirring and scraping off the bottom of the pan with a wooden spoon.

Step 10

As you finish adding the milk, increase the heat to medium.

Step 11

Add napa cabbage and mushrooms and coat them well with the white sauce.

Step 12

Scoop and reserve ¼ cup of cooking pasta water and add it to the white sauce. Stir to loosen it up. Now put the lid on and cook covered on low heat for 3-5 minutes until the napa cabbage and mushrooms are tender. Make sure the lid is tight-fitting so the moisture will not escape (the white sauce will thicken and may burn if the moisture escapes).

Step 13

By now, pasta should be done cooking. Drain well and set aside.

Step 14

Open the lid and see if the cabbage and mushrooms are tender. Season the sauce with salt and pepper (Make sure the sauce is not bland at this step as we will add pasta, which will dilute the flavor a bit).

Step 15

Add the pasta and mix well together.

Step 16

Sprinkle the cheese and then panko evenly on top. If your skillet is not oven-safe, move the mixture into a large baking dish.

Step 17

Preheat the oven broiler to high (550ºF/288 ºC) for 3 minutes. Place the baking dish in the middle rack of the oven, about 8" (20 cm) away from the heating element. Broil until the top gets nicely browned, usually just several minutes, and remove from the oven. Don't leave the kitchen and stay in front of the oven to see the broiling process.

Step 18

Cut the fresh parsley and sprinkle on top. Serve warm.

Step 19

You can keep the leftovers in an airtight container and store in the refrigerator for up to 3 days and in the freezer for a month.