Preheat your oven to 375°F (190°C), and generously butter your baking dish to prevent sticking.
Add the bread cubes to a large mixing bowl and toss with the cooked vegetables, shredded cheese, and chopped herbs, distributing evenly.
In a separate bowl, whisk together the eggs and heavy cream until thoroughly combined and slightly frothy.
Pour the custard mixture over the bread and vegetable mixture, gently pressing down to ensure all pieces are immersed and soak up the custard.
Season with salt and pepper to taste, then let the mixture sit for 10 minutes to allow the bread to absorb the custard fully.
Transfer the soaked mixture into the prepared baking dish, spreading it evenly with a spatula.
Bake in the preheated oven for about 35 to 40 minutes, or until the top is golden brown and the mixture is puffed and set in the center with a slight jiggle.
Remove from the oven and allow to rest for 5 minutes, which helps it set perfectly and makes it easier to slice.
Slice into portions and serve warm, enjoying the creamy interior with a crisp, golden crust on top.