Preheat your oven to 325°F and place the rack in the middle position. Prepare a 12-cup Bundt pan by spraying liberally with nonstick baking spray.
In a medium skillet, place chopped pecans over medium heat and toast until fragrant and nutty, about 6-8 minutes. Set aside and cool for 10 minutes.
In the bowl of your stand mixer fitted with the whisk attachment, add butter and both sugars and mix on high speed for 4 minutes, until fluffy and pale.
Reduce speed to medium and add eggs one at a time, combining well after each egg, and scraping down the sides and bottom of the bowl as needed.
Add the sweetened condensed milk and mix until incorporated.
Reduce the mixer to its lowest speed and slowly add flour and salt to the batter in two increments. Be careful not to overmix here.
Lastly, add in the sour cream, vanilla, and cooled pecans, scrape down the sides of the bowl and mix until just combined. Turn off mixer.
Pour batter into the prepared pan and bake for 1 hour and 15-20 minutes, or until a toothpick inserted in the center of the cake comes out clean.
Remove the cake from the oven and cool in the pan for 10 minutes. Then invert the cake onto a serving plate and continue cooling until completely cooled, about 1 hour.