Preheat oven to 375 F. Line a 9 x 9-inch baking pan with parchment paper making sure to have overlap on the sides for easy removal from the pan.
Whisk oats, flour, sugars, baking soda & salt together. Add buttermilk, oil, egg, vanilla, millet & dates. Whisk to blend. Stir in 1/3 cup boiling water & let stand for 5 minutes. Scrape into baking pan & level out with a fork.
Bake cake 25-30 minutes or until tester inserted into center comes out clean. Cool 10 minutes on a wire rack. During the cooling stage drizzle cake with lemon curd if you wish. Slice & serve warm or at room temperature.