Preheat your oven to 350 Degrees F, or light charcoal briquettes in a chimney.
Add the berries to a large bowl. Add the sugar. Mash the berries until the sugar is evenly incorporated.
Add the cake mix to a different bowl. Whisk the can of Dr. Pepper into the cake mix until completely mixed.
Lightly oil the dutch oven. Pour the berry mixture into the bottom of the dutch oven. Pour the cake mixture over the top of the berry mixture. Make sure the berry mixture is completely covered by the cake batter.
Place the lid on the dutch oven, and bake for 45 mins to an hour. If you are using charcoal, I usually recommend about 6-8 briquettes on the lid, and another 6-8 under the dutch oven. Don't add too many briquettes to the bottom or the berry mixture could burn. Using briquettes will still take about 45 minutes to an hour. Check it every 20 minutes to be safe.
Pour the chocolate chips on top of the cake. Put the lid back on the dutch oven for 5 minutes to let the chocolate chips get melty. Serve, and enjoy with a scoop of vanilla ice cream