Make the dulce de leche the day before or the same day well before you're wanting to serve the cake.
Remove the label from a 14 oz. can of sweetened condensed milk.
Fill a large pot with water and place the unopened can in the water, making sure the top of the can is covered with at least 1 inch of water.
Bring the water to a simmer, then reduce the heat to low. Set a timer for 1 ½ hours.
After 1 ½ hours, flip the can with tongs and heat the sweetened condensed milk for an additional 1 ½ hours. Add more water as necessary to keep 1 inch of water above the can.
After the total 3 hours, remove the can from the water with tongs and let the can cool completely. Once it is completely cool carefully open it. Stir to combine and set aside until ready to use.
For the Pumpkin Bundt
Preheat the oven to 350 degrees. Spray a large, 10-cup capacity Bundt pan with non-stick spray. Set aside.
In a large bowl, cream the softened butter and granulated white sugar together with an electric mixer.
Then add in the eggs and vanilla and mix until pale and fluffy, about 1 minute.
Next mix in the pumpkin puree and buttermilk.
In a separate bowl, whisk together the flour, pumpkin pie spice, baking powder, baking soda and salt.
Add the dry ingredients to the wet ingredients a little at a time and mix until all is completely combined.
Pour the batter into the prepared Bundt pan. Bake the cake for 60-70 minutes, or until a cake tester/toothpick comes out clean from the center with just a few moist crumbs.
Let the cake cool in the pan for at least 30 minutes. Then turn the pan over onto a cooling rack and let the cake completely cool.
Once the cake is completely cooled, pour the dulce de leche over the top and serve!
Store leftovers in an airtight container for up to four days.
Notes
Store leftovers in an airtight container for up to four days.