Preheat the oven to 350°F (175°C).
Grease and flour two 9-inch round cake pans.
In a large mixing bowl, cream together the softened butter and sugar until light and fluffy.
Add the eggs one at a time, mixing well after each addition.
Stir in the buttermilk and vanilla extract.
In a separate bowl, whisk together the flour, baking powder, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, mixing on low speed.
Fold in the toasted pecans and caramel sauce gently.
Divide the batter evenly between the prepared pans.
Bake for 25-30 minutes, or until a toothpick comes out clean.
Let the cakes cool in the pans for 10 minutes, then transfer to wire racks.
Once cool, frost with your favorite buttercream or additional caramel sauce.