Adjust oven rack to middle position. Heat oven to 275°F (130°C). On a rimmed baking sheet, spread bread in an even layer and bake, rotating sheet and stirring bread cubes several times during baking, until bread is completely dried, but not browned or changed in color, 30 to 40 minutes. Remove from oven and set aside to cool. Adjust oven temperature to 350F (175C).

In a large bowl, add eggs, egg yolks, granulated sugar, vanilla extract or scraped vanilla seeds, citrus zest, if using, and salt and whisk to combine. Whisk in cream and milk (or half and half) until combined. Stir in bread and dried fruit and/or nuts, if using, and let sit, pressing down on bread occasionally, for 5 minutes. Stir gently to combine, ensuring the cubes of bread left unsubmerged on the top are now submerged on the bottom, and press gently on bread occasionally until bread is saturated and custard is mostly absorbed, about 5 minutes more.

Carefully transfer mixture to a 13- by 9-inch baking dish and gently press cubes into custard. Using a pastry brush, dab melted butter over top of bread.

In a small bowl, combine the remaining 1 tablespoon sugar and remaining ¼ teaspoon cinnamon and sprinkle the cinnamon-sugar mixture evenly over top.

Place bread pudding on a rimmed baking sheet and bake until custard has just set, top is lightly browned and crisp, and pressing center of pudding with finger reveals no runny liquid, about 30 minutes. (An instant-read thermometer inserted into center of pudding should read about 170℉; 75℃.) Transfer to wire rack and cool until pudding is set, about 30 minutes. Serve warm.