2 cups fresh or frozen cranberries (8 ounces)
1 cup granulated sugar
1 tablespoon water
1/2 cup (1 stick) unsalted butter
2/3 cup firmly packed dark brown sugar
1/2 cup milk
1/2 cup molasses
1/4 cup golden syrup (or date syrup, honey, or sugar)
1-1/2 cup all-purpose flour
1 tablespoon ground ginger
1/2 teaspoon ground cinnamon
1/2 teaspoon baking powder
1/2 teaspoon kosher salt
1/4 teaspoon baking soda
1/4 teaspoon freshly ground black pepper
2 large eggs, lightly beaten
1 tablespoon grated fresh gingerroot
Preheat the oven to 350°F. Butter an 8x8- or 9x9-inch square baking pan generously. Line the bottom with parchment paper.
In a small, heavy-bottomed saucepan, stir together the cranberries, granulated sugar, and water. Stir the slushy mixture over medium heat until the sugar is completely dissolved and the cranberries form a sauce that is syrupy and bubbling thickly, 8 to 10 minutes. Aim to have about half of the cranberries broken down, with the remainder more or less whole. Remove from the heat and set aside.
In a separate small saucepan, combine the butter, brown sugar, milk, molasses, and golden syrup over medium heat. Stir until the butter has melted and the mixture comes to a bare simmer, and then remove it from the heat. Don't let it boil or the mixture could curdle.
In a large bowl, sift together the flour, ground ginger, cinnamon, baking powder, salt, baking soda, and black pepper. Beat in the butter-molasses mixture, and then beat in the eggs. Stir in the grated gingerroot.
Pour the batter into the pan. Drop fat dollops of cranberry sauce onto the surface of the batter. Drag a long, slender knife through the batter in a swirly design, as if you are marbling a cake. Transfer the cake to the oven and bake until the top is firm and a toothpick inserted in the center comes out clean, 50 to 55 minutes. Let cool completely on a wire rack before serving.