Swiss Chard and Gruyere Strata is a make-ahead vegetarian breakfast casserole that's perfect for feeding a crowd. Loaded with veggies, eggs, cheese, and crusty bread, this breakfast bake soaks overnight in your fridge and bakes up in the morning. Leftovers freeze like a dream, and this is also a fantastic packed lunch.
Add the onion, and sauté for about 3 minutes, until translucent.
Add the Swiss chard, and sauté until wilted and the stems are slightly browned. Season with salt and pepper and remove from the heat.
Pour the custard over top of the strata layers. Cover with plastic wrap, and set in the fridge overnight or for at least four hours, but up to one day.