Preheat oven to 350 degrees.
Spray a 9-inch round cake pan generously with cooking spray.
Spread the slices peaches evenly along the bottom of the pan.
Sprinkle the peaches evenly with 1/4 cup of the sugar.
With a hand or stand mixer, beat together the butter and remaining 1 cup of sugar until pale and fluffy, about 3 minutes.
Add the eggs and vanilla and beat until smooth.
In a clean bowl, whisk together the flour, baking powder, salt and pecans.
Add half the flour mixture to the butter mixture and beat on low speed until combined.
Add the sour cream and beat on low speed until combined.
Add the remaining flour mixture and mix until combined, using a spatula to scrape down the sides of the bowl to make sure the batter is evenly mixed.
Spread the cake batter evenly on top of the peaches and sugar, smoothing the top.
Bake for 35 - 40 minutes or until the top of the cake is lightly browned and springs back when gently pressed in the middle.
Allow the cake to cool in the pan for about 15 minutes.
Run a knife around the edge of the cake and invert onto a plate.
Allow to finish cooling before slicing and serving.