
Oloroso is a dry style of sherry, a fortified wine from the Jerez region, aged oxidatively in contact with air, without a cap of flor yeast.
Dry, oxidative and nutty is the profile, and sweetness is the thing to check: bottles under similar names run from bone dry to dessert-sweet. A sweetened one needs the syrup taken out of the recipe rather than added.
Cream sherry / sweet sherry
The sweet style is the same oloroso with sugar added. Use it in place of the dry one and the drink lands distinctly sweeter: drop the syrup from the build entirely, and a dash of lemon often helps.
Also dry and nutty, but it starts as fino under flor and only later ages oxidatively, which leaves it lighter. Oloroso never sees flor and is denser and stronger, so it takes over a drink where amontillado sits alongside the spirit.
Once opened, the sherry keeps in the fridge for several weeks — longer than table wine. The flavor does slowly dull over time.