01 - Preheat oven to 350°F. Grease a 12-cup muffin tin thoroughly or line with cupcake liners for easy removal.
02 - Whisk together flour, baking powder, baking soda, salt, and chopped lavender in a medium bowl until evenly combined.
03 - Beat softened butter and granulated sugar in a large bowl until light and fluffy, approximately 2-3 minutes.
04 - Incorporate eggs one at a time, mixing well after each addition. Stir in vanilla extract until fully blended.
05 - Whisk together whole milk and sour cream in a small bowl until smooth.
06 - Add flour mixture to butter mixture in three portions, alternating with milk mixture, starting and ending with flour. Mix until just combined—do not overmix.
07 - Toss blueberries with 1 tablespoon flour, then gently fold into the batter until distributed evenly.
08 - Divide batter among prepared muffin cups, filling each approximately two-thirds full.
09 - Bake for 22-25 minutes until a toothpick inserted into the center comes out clean.
10 - Let cakes cool in the pan for 5 minutes, then transfer to a wire rack to cool completely before glazing.
11 - Whisk powdered sugar and lemon juice until smooth. Drizzle over completely cooled cakes just before serving.