Preheat the oven to 350 degrees F. Grease a standard 12-cup muffin pan or line it with paper baking cups.
In a medium bowl, mix together the all-purpose flour, baking powder, baking soda and salt.
In a large bowl, add the butter, brown sugar, white sugar, and lemon zest. Using a stand-up mixer with the paddle attachment, cream the butter, sugars and zest together until light and fluffy, about 3 to 5 minutes. Add the ricotta, milk, olive oil, egg, lemon juice and vanilla; beat once more until thoroughly combined.
In two batches, add the dry ingredients, and mix until just combined, being sure not to over mix (this will result in tough muffins).
Divide the batter evenly among the muffin tins (filling them about 3/4 of the way full) and transfer to the oven to bake for 17-20 minutes, until the tops are lightly golden brown and when a skewer is inserted into the center it comes out clean. Transfer the muffins on a cooling rack. While the muffins are cooling, make the glaze.
To make the glaze, warm the 1/4 cup of milk, along with the rosemary, in a small saucepan. When it reaches a light simmer, remove from the heat and allow it to steep for 10 minutes. Remove the sprig of rosemary and pour the milk into the powdered sugar; whisk until smooth. Spoon about a teaspoon or two over each muffin and garnish with a bit of fresh meyer lemon zest.