- 1 ¼ sticks unsalted butter, softened
- ¾ cup packed light-brown sugar
- 2 Rio Star Grapefruit, sectioned
- 1 ½ cups flour
- 1 ½ teaspoons baking powder
- 1 teaspoon ground cinnamon
- ¾ teaspoon ground ginger
- ½ teaspoon baking soda
- ¼ teaspoon ground allspice
- ½ cup granulated sugar
- 2 large eggs
- 1 teaspoon vanilla extract
- ½ cup milk
- Preheat oven to 350 degrees. Put 4 tablespoons butter in a cast-iron skillet or medium baking pan. Place the pan in the oven just long enough to melt butter. Remove pan from oven; scatter ½ cup brown sugar evenly over melted butter.
- Arrange grapefruit sections to cover bottom of pan.
- In a bowl, stir together flour, baking powder, cinnamon, ginger, baking soda, and allspice. In a separate bowl, using an electric mixer, beat remaining 6 tablespoons butter until creamy. Add granulated sugar and remaining ¼ cup brown sugar; beat until well combined. Beat in eggs, one at a time. Beat in vanilla. Alternately add dry ingredients and milk to butter mixture, beginning and ending with dry ingredients.
- Pour batter over grapefruit sections in pan. Bake 45 minutes or until a toothpick inserted in center comes out clean. Cool 5 minutes, then turn cake out onto serving plate. Serve warm.