Preheat oven to 325 degrees. Spray a 10 inch bundt pan with non-stick cooking spray. Dust the bundt pan with 2 T. all-purpose flour. Tap out any excess flour. This will help keep the cake from sticking. Set aside.
Peel and dice 3 cups of peaches. Add in the 5 tablespoons of brown sugar and stir to coat the peaches with the brown sugar. Set aside while making cake batter.
In a large mixing bowl, add in the butter and both sugars. Mix until light and fluffy, about 3 minutes.
Add in the vanilla bean paste and each egg one at a time until incorporated. Scrape down the sides after each egg.
In a separate bowl, add in the flour, baking powder, baking soda and salt. Stir to combine.
Measure out buttermilk and add in the sour cream.
Alternately add the flour and buttermilk/sour cream always starting and ending with the flour. I did 3 parts flour and 2 parts buttermilk. Scrape down the sides and mix to combine.
Strain out the peaches and save the syrup.
Stir the strained peaches into the batter until they're thoroughly incorporated.
Pour the batter into the prepared bundt pan. Spread out evenly.
Place into the preheated oven and let bake for 1 hour 15 minutes or until a skewer comes out with moist crumbs.
Let the cake cool for about 20 minutes. Turn the cake out onto a wire rack and cool completely.
Once cooled, add the cake to a cake plate.
Use a pastry brush or basting brush, brush all of the peach syrup that we saved when we drained the peaches onto the cake. Be sure to cover all of the cake and use all of the syrup. It will leave your cake shiny and take off all the white spots from the flour.
In a saucepan, add in the brown sugar, butter, and heavy cream. Stir to combine. Place over medium/high heat and let it come to a boil. Boil for 5 minutes, stirring occasionally.
Remove from the heat and add in the vanilla and bourbon. Stir to combine. Let cool for 20 minutes so it thickens slightly.