In a large bowl, combine sugar + orange zest + orange juice. Rub together with your hands until fragrant.
Add butter, oil, and vanilla. Beat ~5 minutes until pale and fluffy.
Add eggs one at a time, mixing well after each.
Mix in Greek yogurt until smooth.
Sift flour + baking powder together. Add to batter and mix just ~10 seconds don’t overmix.
Pour into a well-greased and floured Bundt pan.
Bake at 350°F for 50–55 minutes.
Toothpick should come out clean.
While cake bakes, combine butter, water, sugar, and vanilla in a saucepan.
Bring to a simmer until sugar dissolves.
While cake is still hot, pour syrup evenly over the cake in the pan.
Let it soak fully before unmolding.
