Grease the baking pan with butter. Cut brioche or panettone in 1-inch slices and evenly distribute in the pan. Crack the eggs in a big bowl. Whisk together the eggs, milk, cream, granulated sugar, brown sugar, vanilla and lemon. Pour evenly over the bread. Cover the pan tightly and store in the fridge until needed (at least 1 hour).
When you're ready to bake the French toast, preheat the oven to 350 degrees F. Remove from fridge and sprinkle with cinnamon, nutmeg, sugar and pieces of cut butter. Bake for 45 minutes for a softer, more bread pudding texture or for 1 hour or more for a firmer, crisper texture.
For compote, pour ingredients together and let simmer until the cranberries are soft and begin to burst, about 7 minutes.
Top French toast with cranberry compote and drizzle with warm maple syrup.