How to Make It
Heat oven to 325° F. Butter a 9-by-5-inch loaf pan.
In a small bowl, whisk together the eggs, vanilla, and zests. In a large bowl, with an electric mixer on medium-high, beat the butter for 2 minutes. Add 1 1/4 cups of the sugar and the salt and beat for 2 minutes. Slowly add the egg mixture. Beat for 3 minutes. Reduce speed to low and slowly add the flour. Transfer the batter to the prepared pan. Bake for 60 to 70 minutes.
Transfer pan to a wire rack to cool for 10 minutes. Using a knife, loosen the cake from pan. Invert it onto the rack. Turn it over again onto a serving plate.
In a saucepan, over medium heat, simmer the cranberries, orange juice, and the remaining sugar until the berries burst, 5 to 7 minutes. Reduce heat to medium-low and simmer for 5 minutes. Strain the syrup into a bowl and stir in the liqueur (if using). Slice the cake and serve with the warm syrup.