Whisk the milk, eggs, sugar and vanilla together in a medium bowl.
Place half of the challah cubes in a 4-5 quart slow cooker, pushing slightly down. Sprinkle with half the raspberries and chocolate chips. Repeat layers.
Pour milk mixture on top, cover and cook on high for 2 hours, or until puffed up and starting to turn golden on top.
You can use fresh or frozen raspberries – frozen ones are a little sturdier and don’t get squished by the bread as fast as fresh ones do, and they’re cheaper.
If you don’t have any challah or brioche bread, you can also use another variety of light and thick bread (like French bread or Texas Toast).
If you don’t have day-old bread, don’t worry. You can use fresh, the casserole could be a little more dense though. If you want instant stale bread, bake your cubed bread at 300°F for 10 minutes, then let cool before using.
The casserole tastes great with pretty much any berry – blueberries are another favorite. Or even diced apple, perfect for fall and winter! When I use apple, I skip the chocolate chips, or use cinnamon chips instead.
I prefer layering the ingredients vs stirring them together in the crock, because that way I can achieve a more even distribution AND I don’t turn all he raspberries into mush.
Pour the milk/egg mix slowly and carefully over the bread and berries to make sure you catch all the bread, or you’ll end up with dry spots in your French toast bake.
Unfortunately, I don’t recommend cooking this on low (I’ve tried several times, and I never managed to cook the casserole through in the middle before the edges started to turn into charcoal). This means you cannot turn this into an overnight kind of deal, but you can definitely get up early in the morning, switch on your crock and hop back into bed. Or drink a cup of coffee in peace and quite, whatever you like best 😉