01 - Preheat oven to 350°F. Grease and flour an 8-inch round cake pan.
02 - Whisk together flour, baking powder, and salt in a bowl. Set aside.
03 - Beat butter and sugar until light and fluffy. Add eggs one at a time, mixing well after each addition. Blend in lavender and vanilla.
04 - Alternate adding flour mixture and milk to butter mixture, starting and ending with flour. Mix until just incorporated.
05 - Pour batter into prepared pan and smooth top. Bake 25-30 minutes until toothpick inserted in center comes out clean.
06 - Simmer water, sugar, and lavender in small saucepan for 3 minutes. Strain and set aside.
07 - Let cake cool 10 minutes in pan. Poke small holes in surface and brush with warm syrup if using. Cool completely.
08 - Combine powdered sugar, lemon juice, and lavender until smooth. Drizzle over cooled cake and allow to set before serving.