Preheat your oven to 350°F (175°C) and prepare your muffin tin by lining it with paper liners or greasing a mini Bundt cake pan.
In a large mixing bowl, whisk together the flour, granulated sugar, baking powder, baking soda, and salt. Sift for lighter crumb.
In another bowl, mix melted butter, buttermilk, eggs, lemon juice, and lemon zest until combined.
Combine the wet and dry ingredients, mixing gently with a rubber spatula until just combined.
Fill muffin cavities or Bundt molds about two-thirds full with batter.
Bake for 18-22 minutes until a skewer comes out clean and tops are golden.
Cool in the pan for 5 minutes; then transfer to a wire rack to cool completely.
To prepare glaze, heat water or milk, steep lavender, then strain.
Whisk powdered sugar with the lavender liquid and optional lemon juice until smooth, adjusting consistency.
Once cool, glaze each mini cake and allow setting for 15-20 minutes.
Garnish optionally with fresh lavender sprigs and extra lemon zest before serving.