Lately I've had intense cravings for sour and tart foods. With my traditionally sweet and salty palate (with nary a deviation), this sudden change in taste took me (and my cupboards) by surprise. The cravings would hit me out of the blue. On long car rides, I suddenly found myself buying sour candy (a rarity for me) and finding myself disappointed at the lack of a face-scrunching flavor punch. "Sour" snacks were hardly sour enough to nix my cravings. After hitting that particular dead end, I turned towards citrus fruits. My grocery cart began filling up with lemons. I was buying six or seven at a time, determined to create a dessert with a sour taste so pungent even I could be satisfied. What I didn't account for was that baking usually includes sugar (and sugar often puts a stop to that sour hit I so desperately craved). I made lemon bars. Lemon cookies. Lemon cupcakes. Lemon poppy seed muffins, twice. Each time a new dessert was attempted, I used less and less sugar and added increasingly more lemon juice or zest. Though they were all delicious in each individual form, they just weren't what I was looking for. They weren't sour. I spent nearly $20 on lemons in a single month, with nothing to show for it. It was a rough period for me, as a baker. I felt defeated, defeated by such a simple craving. I assuaged my sorrows by eating lemon slices, but it was hardly the spectacular dessert I had imagined. During my next foray to the supermarket, the grapefruit found me. I'm on sale, they shouted at me. Buy us! Eat us! We will be sour enough for you! The grapefruit was, in fact, right. If ever a food should scream out at you from the supermarket shelves, do take heed. Paired with a sour, plain Greek yogurt, I found my breakfast of champions. It was only a small step to turn these ingredients into a tart (and softly sweet) cake. This cake is fresh, bright, with a flavor you can truly appreciate whether you simply love a good grapefruit or have spent a month and unaccountable dollars trying to replicate. This Grapefruit Cake with Grapefruit Buttercream has an original flavor, both clean and pure. After the warm cake emerges from the oven, it is brushed with grapefruit juice which soaks deep into the layers, making an unbelievably moist and tender cake (with just a hint of true tartness). The Grapefruit Buttercream lends a sweeter aspect to this cake. Made with a grapefruit juice reduction, the sourness of the juice balances out the sweetness of the powdered sugar. This cake itself, however, is the true star and is lovely when enjoyed in the afternoon, when the sun is bright and thoughts of spring are on your mind.