Preheat your oven to 450°F (232°C) and prepare a baking sheet with parchment paper.

In a coffee grinder, combine a few tablespoons of sugar with dried culinary lavender and grind until finely blended.

In a large mixing bowl, whisk together flour, baking powder, baking soda, and salt until well combined.

Gently stir in lavender sugar along with remaining sugar into the dry ingredients until just blended.

Cut the cold, diced unsalted butter into the flour until it resembles small peas.

Make a well in the mixture and pour in the cold buttermilk; combine gently with a spatula.

Transfer the dough onto a floured surface and pat it down to about 1 inch thick.

Cut the dough into rounds with a biscuit cutter and chill the cut biscuits in the freezer for about 10 minutes.

Brush the tops of the chilled biscuits with milk and sprinkle with coarse sugar if desired.

Bake for 12-15 minutes or until risen and golden brown.