Spread two pieces of foil on the ground near your fire or grilling chimney, one for piling coals and one for cooking. The cooking foil should be big enough to place the entire dutch oven on top of it.
Heat coals in chimney or campfire until white but not disintegrating.
While coals are heating, mix your cobbler in the dutch oven.
Line the dutch oven with the liner (or parchment). This is not 100% necessary but makes for handy cleanup.
Toss blueberries (or fruit of choice) with sugar and lemon zest and pour into dutch oven.
Mix dry ingredients in a bowl and add milk.
Spoon the flour and milk mixture over the top of the fruit in the dutch oven.
Spread the butter pieces over the top of the batter.
Put the lid on the dutch oven.
Pour coals into a pile on one piece of foil. Using tongs or a small shovel, place 4-5 pieces of coal on the 2nd piece of aluminum foil and set the dutch oven on top of the coals.
Add 5-10 hot coals on top of the dutch oven lid.
Bake for 20-25 minutes or until golden brown and bubbling (add or remove coals from the top to adjust temperature)
Serve with scoops of vanilla ice cream or whipped cream.