Bring water to a boil in a large heavy pot; add a generous pinch of salt. Whisk together buckwheat flour and cornmeal to combine in a small bowl. Pour both flours into boiling water, whisking constantly, until combined. Cook, stirring occasionally, until polenta is tender and very thick, about 15 minutes. Whisk in butter.
Pour hot polenta onto a wooden cutting board. Top with dollops of mascarpone, and a sprinkling of walnuts and pomegranate. Season with salt and pepper. Drizzle with olive oil, if desired.
Before her diagnosis, Caroline wrote a book on cakes called Cake Magic!. She started developing a birthday cake using her gluten-free mix found in that book. Check out other recipes she’s developing for her new life—and the stories behind them—on her blog, The Wright Recipes. Her next book, Catalan Food, written with chef Daniel Olivella, comes out in early September from Clarkson Potter.