First Step: In a large bowl, cream together ¼ cup unsalted butter, 4 ounces cream cheese, and 2 cups granulated sugar until light and fluffy.

Second Step: Add 3 eggs and 1 egg white one at a time, beating well after each, then stir in 1 tablespoon vanilla extract.

Third Step: In another bowl, whisk the remaining flour (from the 3 cups total) with 1 teaspoon baking powder, ½ teaspoon baking soda, and a pinch of salt.

Fourth Step: Alternately add the flour mixture and 1 cup buttermilk to the creamed mixture, beating until just combined, then gently fold in the peaches.

Fifth Step: Pour half the batter into the prepared pan, sprinkle with half the cinnamon sugar mixture, add the remaining batter, and top with the rest of the cinnamon sugar. Swirl with a knife for a marbled effect.

Sixth Step: Bake for 55 to 65 minutes, or until a toothpick inserted comes out clean. Cool in the pan for 15 minutes, then remove and cool completely on a wire rack. Dust with powdered sugar before serving if desired.