Preheat oven to 350 degrees.
In a large mixing bowl, blend peanut butter, pumpkin and egg until creamy. (I did all the mixing by hand.)
Add baking soda, cinnamon, and salt.
Stir until all ingredients are thoroughly combined. Add honey and mix until fully incorporated.
Stir chocolate chunks into the batter.
Spread batter into a lightly greased, 10-inch cast iron skillet.
Bake for 35 minutes or until edges become golden and center is just firm. I covered with a piece of foil for the last 5 minutes to prevent the top from becoming too brown. (All ovens vary so peek a bit early to see if needed.)
Remove from oven and allow to cool for about 5-10 minutes.
Serve warm with vanilla ice cream, if desired.