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 - In a large bowl, beat softened butter and granulated sugar until light and fluffy, approximately 3-4 minutes.
04 - Beat in eggs one at a time, mixing well after each addition. Stir in chopped lavender and vanilla extract until fully incorporated.
05 - Alternately add flour mixture and milk to butter mixture, beginning and ending with flour. Mix until just combined, being careful not to overmix.
06 - Transfer batter to prepared pan, spreading evenly with an offset spatula to smooth the surface.
07 - Bake for 25-30 minutes or until a wooden toothpick inserted into the center comes out clean.
08 - While cake bakes, combine water, sugar, and lavender in a small saucepan. Simmer for 3 minutes, then strain through a fine-mesh sieve. Set aside to cool slightly.
09 - Allow cake to cool in pan for 10 minutes. If using syrup, poke small holes across surface with a skewer and brush warm syrup evenly over cake. Cool completely in pan.
10 - Whisk powdered sugar, lemon juice, and chopped lavender in a small bowl until smooth and pourable.
11 - Drizzle glaze over completely cooled cake, allowing it to drip down the sides. Let glaze set for 15-20 minutes before slicing and serving.