Grease a large casserole dish with butter. A 9x13-inch dish works well for this recipe. Set the casserole dish aside.
Chop the bread into 1-inch chunks. Transfer the chunks into a large bowl.
Chop the figs into quarters. If using large figs, chop them into smaller pieces.
Spread half of the bread chunks into the greased dish. Top with half of the chopped figs. Add the remaining bread chunks to the dish, and then top with the remaining figs.
Beat the eggs in a large bowl. Whisk in the milk, sugar, and lemon zest and mix until all the ingredients are well incorporated. Carefully pour the egg and milk mixture over the bread and figs.
Cover the casserole dish with plastic wrap and refrigerate overnight.
When you are ready to bake the French toast casserole, preheat the oven to 375ºF. Position an oven rack to the center position.
Melt 5 tablespoons of butter in a saucepan. Turn off the heat and mix in the sugar and cinnamon.
Remove the French toast casserole from the refrigerator and unwrap the pan. Using a large spoon, drizzle the melted butter mixture over the casserole. Sprinkle 2/3 cup of raspberries over the bread chunks.
Bake the casserole for 33 to 40 minutes, until the bread on the top of the casserole is brown and crisp.
Let the casserole cool for 5 minutes before serving. Serve the casserole with more raspberries and maple syrup.