Preheat your oven or grill to 400ºF.*
Create an 8-inch x 8-inch tin foil pouch and spray it with nonstick cooking spray. Set aside.
Prepare the peaches by chopping them (keep skin on) and placing them into a large bowl. Squeeze a half a lemon on top and sprinkle on 2 tablespoons brown sugar. Toss.
Next, make the crisp topping. Add oats, flour, pecans, maple syrup, butter, cinnamon, nutmeg, and salt to a medium bowl. Mix well to create your crumble topping.
Layer the peaches and crumble topping into the tin foil pouch by first adding half of the peaches to the pouch and then 1/3 of the crumble topping over the peaches. Then, add the rest of peaches followed by the last 2/3 of the crumble topping.
Fold the top of your tin foil pouch over the peach crisp and seal the edges with your fingers making sure there are no holes for air to escape from.
Grill or bake foil pack peach crisp at 400ºF for 17-22 minutes or until the top of your crisp topping is a golden brown and the peaches are bubbly.
Let cool for 2-3 minutes, and serve with a scoop of vanilla ice cream.