Step 1Prepare the coals without starter fluid in a chimney starter: For a 4-quart (10-inch) Dutch oven, you will need 27 coals hot enough to have formed a thin coating of white ash over the surface of each coal.
Step 2Combine the peaches and blackberries in the Dutch oven, and toss with 2 tablespoons maple syrup, the almond extract and orange zest.
Step 3Separately, combine the flour, oats, almond meal, nutmeg, cinnamon and salt. Stir in the softened butter, then the remaining maple syrup, until you have a crumbly mixture. Sprinkle the crumble over the fruit, then cover with the lid.
Step 4Place the oven over nine of the hot coals (evenly spaced), and evenly space 18 coals over the lid. Cook until the crumble topping is a rich golden color and the fruit is soft, 15 to 20 minutes. Serve immediately.