The Hazelnut Rhubarb Coffee Cake is a beautifully balanced breakfast or brunch treat, offering a delightful interplay of tart and sweet. Tangy rhubarb chunks are folded into a moist, buttery cake, while a crisp topping of golden brown sugar, cinnamon, and chopped hazelnuts adds a crunchy, nutty contrast. Each bite combines rich, comforting cake with bright, fruity flavor and satisfying texture—perfect for a cozy morning gathering or an indulgent afternoon coffee break.