Preheat the oven to 325°F (163°C) and grease two mini cake trays well with baking spray.

Whisk together the flour, salt, and baking soda in a bowl. Set aside.

Beat the butter, granulated sugar, brown sugar, and lemon zest on medium speed for about 3 minutes until light, fluffy, and pale.

Add the eggs one at a time, mixing well after each addition. Scrape down the bowl if needed.

In a separate bowl, whisk together sour cream, milk, and vanilla until smooth.

With the mixer on low, add the dry ingredients and sour cream mixture in alternating batches, starting and ending with the dry. Mix just until combined. The batter should be thick but smooth—avoid overmixing.

Divide the batter evenly into the pans and tap gently to release air bubbles. Bake for 18–20 minutes, until a toothpick inserted comes out clean.

Let the cakes cool in the pans for 10 minutes, then transfer to a wire rack and cool completely.

Heat the milk until hot but not boiling, add lavender, and let it steep for 10 minutes. Strain.

Mix powdered sugar, salt, and vanilla, then gradually add the lavender milk until smooth and pourable. Drizzle over cooled cakes and garnish as desired.