• Preheat the oven to 350°F and grease a 9×13 inch pan.

For Filling

• Peel the peaches then cut into 1-2 inch chunks. You’ll need 7 cups.
• In a large bowl, stir the peach chunks, brown sugar, flour, lemon juice, and cinnamon together until thoroughly combined. Set filling aside as the oven preheats.
• Spoon the peach filling into the pan.

For Crumble

• In a medium bowl, combine the brown sugar, cinnamon, and flour. Stir in the butter and walnuts, if you're using them. The crumble topping will be thick and crumbly. Sprinkle over peaches.
• Place in the oven and bake for 40-50 minutes or until peach juices are bubbling on the sides.
• Allow the pie to cool for 5-10 minutes then serve with vanilla ice cream.