Serves 8 to 10
Start to finish: 15 minutes prep time, plus 3 to 4 hours on low, plus 30 minutes to cool
Slow cooker size: 5 to 7 quarts
2½ cups heavy cream
2½ cups whole milk
9 large egg yolks
¾ cup (5¼ ounces) granulated sugar
4 teaspoons vanilla extract
2 teaspoons grated lemon zest
¾ teaspoon salt
1 pound challah, cut into 1-inch pieces (12 cups), staled overnight
2 tablespoons packed brown sugar
½ teaspoon ground cinnamon
Pinch ground nutmeg
Line slow cooker with aluminum foil collar and lightly coat with vegetable oil spray. Whisk cream, milk, egg yolks, granulated sugar, vanilla, lemon zest, and salt in large bowl until sugar has dissolved. Stir in challah and let sit, pressing on bread occasionally, until custard is mostly absorbed, about 10 minutes.
Transfer challah mixture to prepared slow cooker and spread into even layer. Combine brown sugar, cinnamon, and nutmeg in bowl and sprinkle over top. Cover and cook until center of bread pudding is set, 3 to 4 hours on low.
Turn off slow cooker and let bread pudding cool, covered, for 30 minutes. Discard foil collar. Serve.
Nutrition information per serving: 470 calories; 258 calories from fat; 29 g fat (16 g saturated; 1 g trans fats); 253 mg cholesterol; 381 mg sodium; 44 g carbohydrate; 1 g fiber; 24 g sugar; 10 g protein.