Heat oven to 350°F. Lightly grease mini-Bundt cake pan.
Stir together water, melted butter, egg and cake mix until blended. Gently fold in blueberries. Spoon batter into pan, dividing evenly.
Bake 20-23 minutes or until toothpick inserted into center comes out clean. Let cool 5 minutes. Invert pan and release cakes.
Glaze: Combine glaze mix, lemon juice and zest until desired consistency. Drizzle over cooled cakes and garnish with fresh lavender, if desired.