Preheat oven to 350 degrees and spray a 9x13 baking dish with pam baking spray, set aside.
Using a medium skillet, melt 2 tbsp of butter over medium heat.
Add the chopped apples, 2 tbsp of brown sugar and 1 tsp of apple pie spice.
Cook, while mixing occasionally, until the apples start to soften and the sugar mixture is thick.
Remove from heat and allow to cool to room temperature.
Using a large bowl, beat together 1 C of butter, ¾ C brown sugar, and sugar until light and fluffy.
Beat in eggs, one at a time until combined.
Using a medium bowl, whisk together the flour, baking powder, 1 tsp apple pie spice, and salt.
Gradually beat in ⅓ of the flour mixture into the wet ingredients. Gradually beat in half of the buttermilk until combined.
Beat in another ⅓ of the flour mixture.
Beat in remaining buttermilk and end with mixing the remaining flour mixture into the batter.
Gently fold in the apples. Pour batter into the baking dish.