The night before making cupcakes, chop 2 sprigs of fresh rosemary and mix with 1 cup milk. Cover and let steep in refrigerator overnight, or for at least 2 hours. When ready to bake, pour milk through a sieve to remove the rosemary. The rosemary can then be discarded.
Preheat oven to 350° and line 2 muffin pans with liners.
In medium bowl, combine dry ingredients: flour, salt, baking powder, and baking soda.
In large bowl, beat butter and sugar on medium speed until light and fluffy, 3 - 5 min. Add lemon juice, lemon zest, and fresh rosemary. Scrape sides as necessary. Add 1 egg at a time allowing each egg to be combined before adding the next. Add vanilla.
Reduce speed to low and alternately add milk and dry ingredients in batches. Beat just until combined. Avoid over mixing.
Divide batter evenly into liners (approx. 2/3 full) and bake for 12 - 15 min. Tops should be lightly golden, or a toothpick inserted into the center should come out clean.
Allow cupcakes to cool 5 minutes in pans, then remove to wire racks to cool completely before frosting. Enjoy!