East/West fusion. This looks like a lot of work, but it’s not really.
butter, for greasing pan
1/2 c fine dry bread crumbs, or toasted wheat germ, divided
1 large head bok choi
1 scallion, finely chopped
5 T unsalted butter, room temperature, divided
2 T all-purpose flour
1-1/4 c milk
1/8 t (freshly) grated nutmeg
salt and pepper, to taste
1/2 c coarsely grated Gruyere (or other) cheese
1/4 c finely grated Parmesan or Romano cheese, divided
1. Place a rack in the upper third of the oven. Preheat oven to 425°F. Lightly butter a 2-quart baking dish (8″ x 8″) and sprinkle with 2 T bread crumbs. Bring a pot of water to the boil.
2. Separate leaves from stems. Cut stems into 1/2-inch pieces. Coarsely chop leaves. Add stems to boiling water and cook for about 5 minutes. Add chopped leaves and cook 1 minute more. Drain in a colander. Rinse with cold water. Dry stems thoroughly and squeeze leaves to get as much moisture out as possible.
3. Saute scallion in 1 T of the butter in a large skillet over medium heat for a couple of minutes, until softened. Add the choi and cook, stirring, until the stems and leaves are coated with butter and scallion. Spread the choi in the prepared baking dish.
4. Melt 2 T of the butter in the same skillet (or use a saucepan) over medium-low heat. Add the flour and cook, stirring constantly for 2 minutes. Switch to a whisk and add the milk in a slow, gentle, steady stream, whisking constantly. Bring to a boil, whisking all the while (this won’t take long). Reduce heat and simmer for about 5 minutes, until the mixture thickens some. You don’t have to stir constantly, but fairly often. Stir in the nutmeg, salt, and pepper. Then add the Gruyere and 2 T of the Parmesan and stir to incorporate.
5. Now, you can do a couple of things here. One, you can add half of the white sauce to the choi and mix them together, then pour the remaining sauce over this. Or, two, you can just pour all of the sauce over the choi. Both ways are good–the first way makes the choi a bit more cheesy.
6. Toss remaining bread crumbs with remaining 2 T of Parmesan and remaining 2 T of butter along with some salt and pepper in a small bowl and blend until mixture resembles coarse meal. Sprinkle this over the gratin and bake about 20 minutes, until bubbly and golden brown.