Add apples to the dutch oven. Cook until the apples begin to release moisture. Add bourbon to the apples. Add maple syrup to the mixture. Allow to reduce until you achieve a syrupy consistency. 

Mix all of the dry ingredients for the topping in a bowl (note: the topping can be made in advance in a bag and then added all at once on the day). Dice cold butter into 1cm cubes. Add butter to dry ingredients and mix with hands until the butter has been roughly incorporated. Add maple syrup and bourbon in equal portions until the mixture resembles wet sand.

Add the topping directly onto the apples in the cast iron, spreading evenly.

Put the lid on the dutch oven and cover the lid with hot coals. You'll be able to smell when the topping starts to caramelize and/or burn. Depending on how hot your coals are the cook times will vary, but be sure to check it after about 15 minutes. Cook until the desired level of caramelization has been reached on the crumble. Allow the crumble to cool off the heat for at least 10 minutes to set up.  

Serve with ice cream (if you've got it) and the remaining bourbon. 

What you'll need:

Filling:

• 8 Granny Smith apples, peeled and sliced (or 2 per person) 
• 1 tsp cinnamon 
• 1/4 tsp nutmeg 
• Dash of salt 
• 1/4 cup brown sugar 
• 1/4 cup maple syrup 
• 1/4 cup bourbon 
• 1/2 lemon juice 
• 1/4 cup butter 

Topping:

• 1 cup all purpose flour 
• 1 cup rolled oats 
• 3/4 cup brown sugar 
• 1 cup chopped walnuts 
• ~1/4 cup maple syrup 
• ~1/4 cup bourbon  
• 1/2 cup butter 

Equipment:

• Leatherman P4 
• Camping Axe
• Shovel
• 10" cast iron dutch oven 

For more cast iron recipes follow Teddy Cosco.