– 1 ½ cups (300 g) light brown sugar, packed – ▢⅔ cup (145 g) vegetable oil – ▢2 large eggs, room temperature – ▢1 cup buttermilk – ▢1 teaspoon kosher salt – ▢1 teaspoon baking soda – ▢1 teaspoon vanilla extract – ▢2 ½ cups (312.5 g) all-purpose flour – ▢1 pound rhubarb, diced (about 3 cups) Rhubarb Sauce – ▢1 pound rhubarb, cut into ½-inch pieces (about 3 cups) – ▢¼ cup water – ▢⅓ cup (67 g) granulated sugar