For the cake: Place an oven rack in the center of the oven. Preheat the oven to 325 degrees F. Butter and flour a 8-by-8-inch glass baking dish.
Whisk the flour, baking soda, salt, baking powder and cinnamon in a medium bowl until blended. Beat the sugar, oil, eggs and vanilla in a separate large bowl to blend. Stir in the chopped peaches. Gradually add the dry ingredients and stir until blended. Pour the batter into the prepared baking dish. Bake until a tester inserted into the center of the loaf comes out with no crumbs attached, about 1 hour 10 minutes. Transfer the pan to a wire rack and cool for 15 minutes. Remove the loaf from the pan and cool completely, about 1 hour.
For the frosting: Beat the butter, cream, 2 tablespoons water and vanilla in a large bowl, using an electric hand mixer on medium speed until light and fluffy. Gradually beat in the powdered sugar until light and creamy, adding extra water, 1 teaspoon at a time, if needed. Spread the frosting over the top of the cooled loaf. Allow the frosting to set for 25 minutes. Cut the loaf into slices and serve.
Recipe courtesy of Giada De Laurentiis