01 - Preheat oven to 350°F. Grease and flour a 9-inch round cake pan or line with parchment paper.
02 - Whisk together flour, baking powder, and salt in a medium bowl until well blended.
03 - Beat butter and sugar in a large bowl until light and fluffy, approximately 3 minutes.
04 - Add eggs one at a time, mixing thoroughly after each addition. Stir in vanilla extract and lemon zest if using.
05 - Gradually add dry ingredients to the wet mixture, alternating with milk. Begin and end with dry ingredients, mixing until just combined.
06 - Gently fold raisins into the batter until evenly distributed.
07 - Transfer batter to the prepared pan and smooth the top surface with a spatula.
08 - Bake for 35 to 40 minutes until a toothpick inserted into the center comes out clean.
09 - Let cake cool in the pan for 10 minutes, then remove and transfer to a wire rack to cool completely.
10 - Dust cooled cake generously with powdered sugar before slicing and serving.