Heat the oven to 180˚C/350˚F. Grease a brownie tin or baking tin lightly with oil and cover with baking paper.
Melt the chocolate with the butter in a double boiler and once all incorporated and smooth, leave to cool off.
Place the lavender and some of the sugar in a pestle and mortar and grind together.
Add the briefly whipped eggs, sugar mixture and flour to the chocolate mixture. Mix everything together, but don't overmix it. Once there are no dry spots stop mixing. Pour the batter in the tin and bake for about 30 minutes in the hot oven.
Leave to cool in the tin before taking it out and onto a cake rack to cool further