Preheat the oven to 350°F. Grease an 8” cake pan with a bit oil, and line the bottom with parchment paper.
In a food processor, grind brown sugar and lavender together for 2 minutes until well incorporated and the essence of lavender permeates the sugar.
Using a fine grater, grate the zest from the lemon and oranges. Set aside.
In a mixing bowl, combine the ground almonds, lavender/sugar mixture and baking powder, mix together well. Add in the eggs, oil and zest, mix well.
Pour batter into the prepared pan, bake in preheated oven for 30 minutes, or until golden brown and toothpick inserted comes out clean. Let cool in pan for 5 minutes, then remove and place on cooling rack for 10 minutes.
To make the icing, bring the water and lavender to a boil in a small saucepan, reduce heat and simmer for 5 minutes. Meanwhile squeeze the juice from the zested lemon and oranges into a cup. Strain out any pulp and seeds. In a mixing bowl, add the icing sugar. Strain the lavender from the water, add the lavender water to the icing sugar, with a whisk mix well. Add the citrus juice and continue mixing until well incorporated and smooth. If your icing is very runny add a bit more icing sugar, a tablespoon at a time. Pour icing over your cake and spread evenly. Enjoy!