• Preheat the oven to 400°F and have a shallow 4-cup gratin or casserole dish ready. The shape of the dish doesn’t matter as long as it isn’t too deep.
• In a small bowl, melt 1 tablespoon of butter and combine it with the breadcrumbs. Season with a pinch of kosher salt and a few cracks of black pepper. Set aside for topping.
• In a medium saucepan, pour in the cream and add the smashed garlic cloves. Bring the mixture to a gentle boil over medium-high heat—keep an eye on it to prevent overflowing. Once boiling, reduce the heat and let it simmer briskly until the cream reduces to about ¾ cup, which should take 4 to 8 minutes. Avoid over-reducing. Remove the pan from the heat, discard the garlic cloves, and stir the cream occasionally to prevent a skin from forming. Let it cool slightly, then season with ¼ teaspoon salt and a few grinds of black pepper.
• While the cream reduces, cook the bacon or pancetta in a large nonstick skillet over medium heat until golden and crispy, around 7 minutes. Transfer to a paper towel-lined plate. Carefully pour off most of the rendered fat from the skillet, but leave behind a thin coating for flavor.
• Add the remaining 1 tablespoon of butter to the same skillet. Once melted, toss in the cooked greens. If you’re using bacon, season with an additional ¼ teaspoon of salt. If using pancetta, you may not need extra salt. Sauté the greens briefly, stirring constantly for about 1 minute to heat them through and blend flavors.
• Transfer the greens to the prepared gratin dish, spreading them evenly across the bottom. Scatter the crisped bacon or pancetta over the greens. Sprinkle the grated cheese over the top.
• Pour the warm seasoned cream evenly across the surface, allowing it to settle between the layers. Finish by topping with the seasoned breadcrumbs.
• Bake in the preheated oven for approximately 25 minutes, or until the top is golden brown and the dish is bubbling around the edges. Allow the gratin to rest for 10 to 15 minutes before serving.

Directions for Preparing and Cooking the Greens

• To yield the 2 cups of cooked greens needed for this recipe, start with the following amounts of raw vegetables. Wash thoroughly in cold water, trim and discard any tough stems, and roughly chop the leaves. Bring a large pot of lightly salted water to a boil, then submerge the greens and cook just until tender (see specific times below). Drain well, then spread on a kitchen towel to absorb excess moisture. If the greens still feel damp, gently squeeze them to remove any remaining liquid.
• Swiss Chard: Begin with 1¾ pounds of Swiss chard. Trim away the stems (save them for soup or sautéed dishes), and chop the leaves to yield about 9½ cups. Boil for 1 minute.
• Spinach: Use 1 pound of mature spinach with stems removed. Chop the leaves to yield approximately 7 cups lightly packed. Cook for 30 seconds, just until wilted.
• Broccoli Raab: Start with 1 pound of broccoli raab. Remove the tough lower stems and any discolored leaves. Roughly chop the rest to yield about 6 heaping cups. Cook for 2 minutes.
• Kale: Use 1¼ pounds of kale with stems trimmed away. Chop the leaves to get 6 cups lightly packed. Boil for 8 minutes.