01 - Preheat oven to 350°F. Grease a 12-cup muffin tin or line with cupcake liners.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, salt, and chopped lavender until well combined.
03 - In a large bowl, beat softened butter and granulated sugar until light and fluffy, about 2-3 minutes.
04 - Beat in eggs one at a time, mixing well after each addition. Stir in vanilla extract.
05 - Combine milk and sour cream in a small bowl, whisking until smooth.
06 - Add flour mixture to butter mixture in three additions, alternating with milk mixture. Begin and end with flour. Mix until just combined, being careful not to overmix.
07 - Toss blueberries with 1 tablespoon flour to prevent sinking, then gently fold into the batter.
08 - Divide batter evenly among prepared muffin cups, filling each about 2/3 full.
09 - Bake for 22-25 minutes, or until a toothpick inserted in the center comes out clean.
10 - Let cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.
11 - For optional glaze, whisk powdered sugar and lemon juice until smooth. Drizzle over cooled cakes.