Preheat the oven to 300˚F/150° Spread the bread pieces on a rimmed baking sheet and toast in the oven for about 30 minutes, until very dry.

Meanwhile, prepare a 5- to 7-quart (4.7 L to 6.6 L) slow cooker: Fold a large piece of foil into a 3 x12-inch (7.5 cm to 30.5 cm) strip and press it against the side of the insert that runs the hottest, using the foil like a collar or a shield. The hot spot is probably the wall of the insert opposite (farthest from) the control panel. This will keep that side of the strata from scorching or cooking too quickly. If your slow cooker runs very hot and tends to overbrown on all sides, line the other side with a foil collar as well. Then line the entire insert with 1 piece of parchment, making sure the parchment comes up at least 2 inches (5 cm) on all sides. This is to prevent sticking and also to make it easier to reach in and remove the strata. (You’re using 1 piece of parchment so that the egg mixture doesn’t run between 2 layers of parchment when you pour it in.)

Bring a large pot of salted water to a boil. Add the kale leaves, give them a stir, cover, and cook until just wilted, about 1 minute. Drain the kale in a colander, run under cold water to stop the cooking, and thorough­ly squeeze the water out with your hands; then blot the kale dry with a kitchen or paper towel. Chop the kale and set it aside.

In a medium bowl or large liquid measuring cup, beat together the eggs and milk. Add the red pepper flakes, salt, and a few generous grinds of pepper.

Put half the bread pieces into the bottom of the prepared insert. Scat­ter all the kale and half of the cheese over the top. Add the remaining bread and top with the remaining cheese. Carefully pour the egg mix­ture all over the top, keeping all the liquid contained in the parchment liner and making sure all the pieces of bread are moistened. Cook until the custard is just set but still jiggly in the middle: on HIGH for 2 hours followed by WARM for 6 hours; on HIGH for 2 hours 30 minutes; or on LOW for 4 hours.

Uncover the slow cooker and turn it off. Let the strata rest for 10 min­utes. Grabbing the edges of the parchment liner, lift the strata out of the insert. Serve warm or at room temperature, cut into wedges.

ALL NIGHT: Holds well on warm through step 5 for up to 30 additional minutes.