For the cake:
8 sprigs pesticide-free fresh lavender flowers, or 1 tsp. finely chopped,
pesticide-free fresh lavender leaves, plus flowers for decorating
1 1/4 cups superfine sugar
16 Tbs. (2 sticks) unsalted butter, at room temperature
Finely grated zest of 2 lemons
Pinch of fine sea salt
1/2 cup sifted all-purpose flour
1 1/2 cups ground blanched almonds
1/4 cup fresh lemon juice
For the icing:
1 1/2 cups confectioners' sugar
Juice of 1/2 large lemon, or as needed
Preheat an oven to 350°F. Generously butter a 9-by-5-inch loaf pan.
To make the cake, strip the flowers from the lavender sprigs. Place in a food processor and add the superfine sugar, butter, lemon zest and salt. Process until pale and fluffy, 2 to 3 minutes. Transfer to a large bowl. Add the eggs one at a time, alternating with one-fourth of the flour, beating well with a wooden spoon after each addition. Gently stir in the ground almonds and the lemon juice.
Spoon the batter into the prepared pan and smooth the top. Bake for 10 minutes. Reduce the oven temperature to 325°F and bake until a skewer inserted into the center of the cake comes out clean, 50 to 55 minutes. Transfer the pan to a wire rack and let cool for about 5 minutes, then run a knife around the edge of the pan and turn the cake out onto the rack. Place right side up and let cool.
Meanwhile, make the icing: Sift the confectioners' sugar into a bowl. Using a wooden spoon, stir in the lemon juice, a few drops at a time. The icing should be thick but spreadable. If it is too stiff, add a little more lemon juice.
Using a knife and dipping it in hot water if it becomes too sticky, spread the icing over the cooled cake, making sure that it drips down the sides. Let stand until the icing is set, about 1 hour. Decorate the cake with fresh lavender flowers. The cake will keep, stored in an airtight container without the flower garnish, for up to 3 days. Serves 8 to 10.
Adapted from Williams-Sonoma A Taste of the World (Gold Street Press, 2008).