Kabocha is a Japanese pumpkin [hard winter squash] with a nutty flavor and natural sweetness. It's like a more intense butternut squash with a texture almost as dense as a sweet potato. I recently saw them in the grocery store labeled "buttercup squash" and if you find them, you should definitely take a couple home. You can dice it and roast it with the skin on, and it can cook in the oven [or toaster oven] while any big piece of meat (roast, whole bird, etc] is resting before carving... it's a great side dish for a holiday meal with very little effort.
If I'm only cooking for two, [and I usually am] I'll cook just a half at a time as a super simple side dish in my toaster oven while I'm working on the stove. I'm highlighting it as a holiday side, but goes with pasta or rice dishes just as well.
Recipe: Roasted Kabocha, "Buttercup Squash"
You can add a sprinkle of whatever spice might tie it in to your main dish, maybe a little thyme or fennel seeds or crushed garlic or red pepper flakes... but it's pretty great with simple salt and pepper.
If you're doing this while a roast or bird is resting, it's better to prep the squash while your meat is still cooking so you can slide it right into the oven after the meat comes out... it won't hurt it if starts cooking before the oven's up to temp.
1 kabocha or buttercup squash
Preheat [or increase] oven to 425F.
Using a sturdy knife, cut the squash half, pole to pole, and remove seeds and fibers. Halve each half and remove the stem end. Dice into ~1/4-1/2" cubes.
Cover a shallow roasting or jelly-roll (half-sheet) pan with aluminum foil and spray with cooking spray. Transfer squash cubes to the pan, spray again with cooking spray, and sprinkle liberally with salt and pepper.
Roast until deep brown spots appear ~20 minutes, stirring once halfway through, if you're not busy setting the table.