Preheat the oven to 350° F and lightly grease an 8×8 or 9×9 square pan.
In a food processor, pulse the sugar and lavender together until well combined.
In a saucepan, on low heat melt the chocolate and butter, while occasionally stirring. Once melted, turn off the heat and stir in the lavender sugar, salt, cinnamon and vanilla extract. Add the eggs until well combined, and then stir in the flour and walnuts, mixing until a smooth, thick batter is formed.
Spoon the batter into the pan. Bake for 25-30 minutes, or until an inserted knife comes out clean. Immediately after removing the brownies from the oven, sprinkle the top with the flaked sea salt. Allow to completely cool for at least an hour before slicing.
Culinary lavender can be found in the spice section at the grocery store, at specialty markets or at the farmers’ market.