Sprinkle the pecans in an even layer into the bottom of the pan
Whisk the butter, brown sugar, karo syrup and salt together in a sauce pan over medium heat until boiling. Continue whisking 15 seconds while it boils.
Add half the dry ingredients and mix on low speed until almost fully incorporated. Add the buttermilk and slowly mix to incorporate. Add the other half of the flour mixture then mix on low just until combined.
Pour the brown sugar sauce mixture evenly over the top of the pecans. Top the pecan mixture with the cake batter in an even layer. Bake for 50-55 minutes.
Allow the cake to cool on a wire rack for 45-60 minutes. Remove the sides from the pan then invert the cake onto a serving platter. Remove the top of the pan from the pecan topping. Serve immediately