01 - Preheat the oven to 350°F (175°C). Grease and flour an 8-inch (20 cm) round cake pan.
02 - In a bowl, whisk together flour, baking powder, and salt. Set aside.
03 - In a large bowl, cream butter and sugar until light and fluffy. Beat in eggs one at a time. Mix in lavender and vanilla.
04 - Alternately add the flour mixture and milk to the butter mixture, beginning and ending with flour. Mix until just combined.
05 - Pour batter into the prepared pan. Smooth the top evenly.
06 - Bake for 25-30 minutes or until a toothpick inserted in the center comes out clean.
07 - Optional: While cake bakes, make lavender syrup by simmering water, sugar, and lavender in a small saucepan for 3 minutes. Strain and set aside.
08 - Let cake cool for 10 minutes. If using syrup, poke small holes in cake and lightly brush with warm syrup. Cool completely.
09 - For the glaze, mix powdered sugar with lemon juice and lavender until smooth. Drizzle over the cooled cake.
10 - Let the glaze set before slicing and serving.