With the rack in the middle position, preheat the oven to 180 °C (350 °F).
Butter a 23 x 13-cm (9 x 5-inch) loaf pan. In a bowl, combine the flour and baking powder.
In another bowl, using an electric mixer, beat the butter, sugar and eggs until the mixture whitens. Add the vanilla and lavender. With a spatula, stir in the dry ingredients alternately with the milk. Spread the batter into the pan.
Bake for about 45 minutes or until a toothpick inserted in the centre of the cake comes out clean. Allow to cool.
In a bowl, blend the icing sugar and water. Pour over the cake, allowing the icing to run down the sides. Sprinkle with the lavender.
You can easily find dried lavender in health-food stores. This type of lavender is specifically designed for cooking uses. Do not use lavender oil or lavender flowers from a pot-pourri!
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.