01 - Preheat oven to 350°F. Grease and flour a 9-inch round cake pan or line with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, and salt until well blended.
03 - In a large bowl, beat butter and sugar together until light and fluffy, approximately 3-4 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 wet mixture, alternating with milk. Begin and end with dry ingredients. Mix until just combined.
06 - Gently fold raisins into batter until evenly distributed.
07 - Pour batter into prepared pan and smooth top with spatula.
08 - Bake for 35-40 minutes until toothpick inserted into center comes out clean.
09 - Let cake cool in pan for 10 minutes, then transfer to wire rack to cool completely.
10 - Dust cooled cake generously with powdered sugar before serving.