Preheat the oven to 350°F (180°C). Grease & flour a bundtlette pan with six 1-cup servings. Make sure to thoroughly grease & flour all of the crevices.
In a med-sized bowl, whisk together the flour, baking powder, baking soda & salt until well blended.
In a large bowl whisk together the sugar & lemon zest until well combined. Add the oil, eggs, & vanilla extract. Whisk until smooth & creamy.
In a small bowl, whisk together the milk & sour cream. Stir the flour mixture into the batter in 2 additions, followed by half of the milk mixture after each addition. Stir just until combined.
Fill the bundt pan wells half full of batter. Bake until the tops are springy & a toothpick inserted in the centers of the cakes comes out clean or with a few crumbs attached, about 14-16 min. Check for doneness a couple of minutes early to avoid over baking.
Cool the cakes in the pan for 8 min., then turn the cakes out onto a cooling rack. Brush the warm cakes generously with lemon simple syrup.
