Step 1

Peel, scrape out the seeds, and cut 1 medium butternut squash into 2-inch pieces (about 4 cups).

Step 2

Prepare the coconut if needed: thaw 3 cups grated frozen coconut or add 1 1/2 cups hot water to 3 cups dried coconut to plump up and rehydrate. Place in a food processor fitted with the blade attachment or high-speed blender (a regular blender will work, but the paste will be grainier).

Step 3

Prepare the following, adding them to the blender as you go: Peel and slice 1 (1-inch piece) fresh ginger. Peel and halve 1 large shallot. Peel 4 garlic cloves. Trim the stems from 3 dried red chiles. Add 2 tablespoons kosher salt and 1 tablespoon coriander seeds. Process or blend, adding a little water as needed to get the blades moving, until a paste forms.

Step 4

Transfer the paste to a large Dutch oven. Add 1 quart water and bring to a simmer over medium-high heat. Add the butternut squash and simmer over medium-low heat, stirring occasionally, until the squash is tender, about 25 minutes. Meanwhile, halve 1 medium lime.

Step 5

Add the shrimp to the curry and cook, stirring occasionally, until cooked through, 5 to 7 minutes. Add 3 cups packed baby spinach, stir to combine, and cook until wilted, about 2 minutes. Remove from the heat, squeeze in the juice from the lime halves, and stir to combine.

Step 6

Heat 2 tablespoons vegetable oil in a small saucepan over medium heat until shimmering. Add 1 tablespoon black mustard seeds. When it sizzles and pops, immediately cover the pan. When the popping starts to subside, add 5 fresh curry leaves. Immediately cover the pan, as moisture from curry leaves will cause the oil to spurt. Once the sputtering stops, stir to evenly coat everything with oil and continue to fry for 10 seconds. Turn off the heat. Pour the spiced oil over the butternut shrimp curry. Serve with cooked rice.