01 - Preheat oven to 350°F (175°C). Grease a 9-inch round cake pan and line the bottom with parchment paper.
02 - Melt 1/4 cup unsalted butter in a small saucepan over medium heat. Stir in light brown sugar and grated ginger until sugar dissolves and mixture bubbles, approximately 2 minutes. Pour this caramel evenly into the prepared cake pan.
03 - Arrange the sliced peaches over the caramel mixture in a circular pattern, ensuring they overlap slightly.
04 - In a medium bowl, whisk together all-purpose flour, baking powder, baking soda, salt, and ground ginger.
05 - In a large bowl, cream softened unsalted butter and granulated sugar until light and fluffy. Beat in eggs one at a time, then incorporate vanilla extract.
06 - Gradually add the dry ingredients to the wet ingredients in three alternating additions with the sour cream and whole milk, beginning and ending with the flour mixture. Mix until just combined, avoiding overmixing.
07 - Gently spread the cake batter over the arranged peaches, smoothing the top surface.
08 - Bake for 40–45 minutes, or until a wooden skewer inserted into the center of the cake emerges clean.
09 - Allow the cake to cool in the pan for 10 minutes. Carefully run a knife around the edges, then invert the cake onto a serving plate and remove the parchment paper.
10 - Serve warm or at room temperature.