Prep oven. Position a rack in the center of your oven and preheat to 350°F/177°C.
Combine dry ingredients. In a large bowl, sift together the flour, baking powder and baking soda. Stir in the salt. Set aside. 2 ½ cups (300 g) all purpose flour ½ teaspoon salt ½ teaspoon baking powder ½ teaspoon baking soda
Cream butter and sugar. In a large mixing bowl with an electric mixer (or a stand mixer fitted with paddle attachment), cream together the butter and sugar until light and fluffy, about 2 to 3 minutes on medium high speed. 1 cup (2 sticks, 226 g) unsalted butter 2 ¼ cups (450 g) granulated sugar
Add eggs and vanilla. Add the eggs one at a time, scraping down the mixing bowl well after each addition and mix until blended. Beat in vanilla until combined. 4 large eggs 2 teaspoons vanilla extract
Alternate dry mixture and sour cream. Add the flour mixture and sour cream alternately to butter-sugar-egg mixture, beginning and ending with the flour mixture until uniformly incorporated- do not overmix. 1 cup (227 g) sour cream
Add peaches. Gently fold in the diced peaches until evenly incorporated into the batter. 1 ½ cups diced peaches
Make and assemble the topping. In a small bowl, stir together the flour, brown sugar and cinnamon. Stir in the melted butter. 2 tablespoons flour ½ cup (107 g) packed light brown sugar 1 teaspoon cinnamon ¼ cup (½ stick, 57 g) unsalted butter
Prep pan. Spray a 10-cup capacity Bundt pan with cooking spray with flour, or grease with shortening and dust with flour.
Assemble. Line bottom of Bundt pan with sliced peaches. Pour topping over the peaches. Pour batter into pan. 1 peach
Bake. Bake in a preheated 350°F oven for approximately 60-65 minutes, until top is golden brown and when the cake is done when a toothpick or skewer inserted in the center comes out clean or with a few moist crumbs. Remove from the oven and cool in the pan for 10 minutes then loosen the edges of the pan with a knife or metal spatula invert onto a wire rack until and remove from the pan. If some of the peaches stick just remove and place back on top of the cake.
Make glaze. In a small bowl, whisk together the glaze ingredients. Adjust consistency if needed. Pour over cooled cake before serving. 1 ½ cups (170 g) powdered sugar 2-3 tablespoons milk 1 teaspoon vanilla extract