Preheat oven to 350 F. Butter or lightly oil an 8″ pan.
In a medium sized bowl, whisk to combine the flour, baking powder, baking soda, and salt. Set aside.
In the bowl of an electric mixer using a whisk attachment, beat the sugar, eggs, until thick, fluffy, and pale, about 3-4 minutes.
Add the lemon zest and chopped rosemary and beat until combined. Slowly add the olive oil with the mixer still running on high. Beat until combined, about 2 minutes. Reduce speed to low and add the milk and lemon juice alternatively with the dry ingredients.
Pour the batter into the cake pan. Bake 30-35 minutes or until a toothpick comes out clean when inserted into the center of the cake (a few crumbs are okay).
Place the pan on a rack and cool in the pan for 10 minutes. Remove cake from the pan and allow to cool completely on the rack.
Once cooled or before serving, dust with powdered sugar or mascarpone whipped cream.