Step 1

Heat the oven to 375°F with a rack in the lower-middle position. Place the bread on a rimmed baking sheet and toss with 3 tablespoons oil. Bake, stirring once or twice, until light golden brown, 10 to 14 minutes; set aside.

Step 2

In a large Dutch oven over medium-high, combine the remaining 3 tablespoons oil, the leeks, garlic and ½ teaspoon salt. Cover and cook, stirring occasionally, until the leeks are softened and lightly browned, 9 to 12 minutes. Add the kale and stir just until wilted. Remove the pot from the heat and stir in the lemon zest and juice, nutmeg and ½ teaspoon pepper. Distribute the mixture in an even layer.

Step 3

Nestle about half of the toasted bread into the leek-kale mixture. Sprinkle half of the cheese over the top, then add the remaining bread in an even layer. Pour the broth around the edges of the pot, pressing on the layers to compact slightly. Top with the remaining cheese. Bake, uncovered, until golden brown and bubbling, 35 to 40 minutes. Cool on a wire rack and for about 20 minutes before serving.

Step 4

Optional garnish: Red pepper flakes OR hot sauce