Preheat your oven to 350°.
Grease the sides of the 9x5 inch loaf pan with softened butter or with cooking spray.
In a large bowl, stir together the white granulated sugar, brown sugar, melted butter, and pumpkin puree.
Stir in the 2 eggs, pumpkin pie spice, salt, and baking soda.
Stir in the buttermilk and flour until just combined.
Gently stir in the chopped Reese's Peanut Butter Cups. Don't forget to save some for the top!!
Pour the batter into the loaf pan and sprinkle more of the chopped Reese's Peanut Butter Cups on top.
Bake for 45-55 minutes and check it often to make sure that you don't over bake it. If you oven bakes hot, check it at 40 minutes.
Let it cool on a wire rack for about 10 minutes before slicing. We like to put butter on it too! I know...it's just a thin layer.