01 - Preheat oven to 350°F and line 12-cup muffin tin with cupcake liners.
02 - Combine milk and lavender buds in small bowl. Let steep 10 minutes, then strain to remove buds.
03 - Whisk together flour, baking powder, baking soda, and salt in medium bowl.
04 - Beat butter and sugar in large bowl until light and fluffy, about 2-3 minutes.
05 - Add eggs one at time, beating well after each. Mix in lemon zest, lemon juice, and vanilla extract.
06 - Alternately add dry ingredients and lavender-infused milk to butter mixture, beginning and ending with dry ingredients. Mix until just combined.
07 - Divide batter evenly among cupcake liners, filling each about 2/3 full.
08 - Bake 18-20 minutes or until toothpick inserted in center comes out clean. Cool in pan 5 minutes, then transfer to wire rack to cool completely.
09 - Beat butter until creamy. Gradually add powdered sugar, lemon juice, lemon zest, ground lavender, salt, and 1 tablespoon milk. Beat until smooth and fluffy, adding more milk as needed for desired consistency.
10 - Frost cooled cupcakes and garnish with extra lavender buds or lemon zest if desired.