Step 1

Preheat the oven to 400 degrees F.

Step 2

Remove the tough, fibrous ribs from the kale leaves and discard the ribs. Tear the leaves into bite-size pieces. Reserve any tender stems and finely chop. Keep the leaves and chopped stems separate.

Step 3

Meanwhile, bring a large pot of salted water to a boil over high heat and fill a large bowl with ice water. Add the kale leaves to the boiling water and cook until tender and bright green, 1 to 2 minutes. Use a slotted spoon or tongs to transfer the kale to the ice water bath. Once completely cool, drain well. Bring the water back to a boil, then add the squash. Cook until just tender, about 3 minutes. Drain well and reserve the pot.

Step 4

Place the pot over medium-high heat. Melt the butter, then add the reserved kale stems, garlic, onion, 1/2 teaspoon salt and several grinds of pepper. Cook until the vegetables are tender, about 4 minutes. Stir in the kale leaves, squash, heavy cream, cream cheese, Parmesan and nutmeg until well combined and smooth. Reduce the heat to medium and cook until the sauce has reduced and thickened slightly, about 5 minutes. Season with salt and pepper.

Step 5

Transfer to a 2-quart baking dish. Stir together the breadcrumbs, parsley and a pinch of salt and pepper in a small bowl until combined, then sprinkle evenly over the top of the casserole. Bake until golden brown and bubbling at the edges, 15 to 20 minutes.