Preheat oven to 350°F (175°C). Grease a 9-inch round cake pan and line with parchment paper.
Mix wet ingredients: In a large bowl, whisk together olive oil, sugar, and eggs until smooth and slightly pale.
Add yogurt and citrus: Stir in Greek yogurt, lemon zest, and lemon juice until creamy.
Mix dry ingredients: In a separate bowl, whisk flour, baking powder, baking soda, salt, and chopped rosemary.
Combine: Gently fold dry ingredients into the wet mixture until just combined. Don’t overmix.
Bake: Pour batter into the prepared pan and bake for 35–40 minutes, or until a toothpick in the center comes out clean.
Cool and serve: Let the cake cool in the pan for 10 minutes, then move to a wire rack. Dust with powdered sugar before slicing.