Preheat the oven to 350°F (177°C). Grease and lightly flour a 10- to 12-cup Bundt pan (I like this one and this one).

Whisk the flour, baking powder, baking soda, and salt together in a large bowl. Set aside. Using a handheld or stand mixer fitted with a whisk or paddle attachment (or you can use a whisk) mix the oil, granulated sugar, brown sugar, eggs, sour cream, and vanilla together until combined. Pour the dry ingredients into the wet ingredients, and beat on medium-low speed or whisk until the batter is completely combined. Batter is thick, yet silky. You should have about 4 cups (1300g) of batter.

In a medium bowl, gently stir the peaches, sugar, and cinnamon until the peaches are coated.

Pour and spread 1/3 of the cake batter evenly into the prepared Bundt pan. Arrange half of the peaches on top (including any juices), and try to keep them in the center of the batter and not touching the edges of the pan. Pour and spread another 1/3 of the cake batter evenly on top, followed by the rest of the peaches. Again, try to prevent the peaches from touching the edges of the pan. Finally, pour the remaining cake batter on top. Use a spatula or back of a spoon to smooth over any exposed peaches as best you can.

Bake for 55–70 minutes or until a toothpick inserted into the cake comes out clean (with just a couple moist crumbs). This is a large, heavy cake so don’t be alarmed if it takes a little longer in your oven. As it’s baking, after 30 minutes, loosely cover with aluminum foil to prevent over-browning.

Once done, place the cake on a cooling rack and allow to cool in the pan for 1 hour. Run a knife around the edges to loosen the cake from the pan, then invert the Bundt cake onto a cooling rack or serving dish and allow to cool completely.

Slice the butter into pieces and place in a light-colored skillet. (Light colored helps you determine when the butter begins browning.) Melt the butter over medium heat, stirring occasionally. Once melted, the butter will begin to foam. Keep stirring occasionally. After 5–8 minutes, the butter will begin browning—you’ll notice lightly browned specks forming at the bottom of the pan and it will have a nutty aroma. Once browned, remove from heat immediately and pour into a medium heatproof bowl or liquid measuring cup. Allow to slightly cool for 5–10 minutes. Whisk in the rest of the icing ingredients until smooth. Add more sifted confectioners’ sugar for a thicker texture, if desired. Likewise, add more milk to thin out if needed. Taste and add another pinch of salt if desired.

Immediately drizzle the icing over the cooled cake. (The icing thickens quickly.) Slice and serve.

Cover leftover cake tightly and store at room temperature for up to 2 days or in the refrigerator for up to 5 days.