Tender chunks of sweet kabocha, umami mushrooms and macaroni in a creamy béchamel sauce, topped off with panko breadcrumbs and baked until crispy golden. Kabocha Gratin with a Japanese twist is the ultra comfort food in cold weather months.
Microwave the kabocha for 2 minutes and remove seeds and pith from the kabocha. To learn more about how to cut kaboha squash, click here.
Cut into wedges and remove the skin.
Cut into small chunks, about 1 inch (2.5 cm) cubes.
Thinly slice the onion and garlic.
Discard the bottom of the shimeji mushrooms. Separate shimeji mushrooms into small pieces with hands.
Cut the oyster mushrooms into 2-inch (5 cm) pieces and slice thinly.
To Make White Sauce
In a large saucepan, melt 4 Tbsp (56 g) butter over low heat. Once the butter is completely melted, add the flour and mix well until blended. Cook the flour, stirring constantly, without browning, for 1-2 minutes.
Gradually add in the warm milk (½ cup at a time), stirring constantly, until the sauce is completely smooth without any lumps.
Season with a pinch of kosher salt, white pepper (or freshly ground black pepper), and nutmeg.
Cook the white sauce, stirring constantly until the sauce has thickened, about 10-15 minutes. It should be a thick creamy sauce. Taste the sauce one more time and adjust the seasonings to make sure it’s not bland. Set aside. Tip: If you end up with leftover white sauce, it can be stored in an airtight container in the refrigerator for up to 3-4 days.
To Cook Kabocha
In a large frying pan, heat 1 ½ Tbsp extra virgin olive oil. Add the garlic and onion and sauté until the onion is coated with oil.
Add the oyster and shimeji mushrooms and cook for 2-3 minutes.
Once the mushrooms are tender, add the miso and mix well together.
Add the kabocha and 1 cup (240 ml) water for steaming. Close the lid and cook kabocha on medium-low heat until it’s tender, about 10 minutes.
To Cook Pasta (if you add macaroni)
Meanwhile, in a large pot of boiling water, add 2 Tbsp kosher salt and cook macaroni according to the package instruction, but cook 1 min less than the instruction as it’ll cook further in the frying pan. Drain well and set aside.
If you’re using a broiler, preheat the broiler for 5 minutes. If you don’t have a broil setting in your oven, preheat the oven to 500ºF (260ºC). Adjust the rack so the food is about 4-6 inches from the heat source.
Insert the wooden skewer to see if it goes through kabocha. If it does, add the white sauce and mix all together.
Taste the sauce and season with salt and black pepper if necessary.
Add the cooked macaroni and mix well.
Grease the inside of your two 8” x 8” (20 x 20 cm) baking dishes rubbing with a stick of butter (I use one of 8” x 8” baking dish and 4 individual gratin dishes). You can also melt the butter and use a brush to grease the dishes. Transfer the mixture to the buttered baking dish(es).
Grate the Gruyere cheese on top and sprinkle some panko.
Place the baking dishes in the oven (broiler or 500 ºF/250 ºC) for 3 to 4 minutes until the top is nicely golden brown and bubbling around the edges. If the dishes are not browning evenly, rotate them around. Remove from the oven and let the gratin stand for 5 minutes, then garnish with chives and serve.
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.