Peel, pit and slice the peaches. Toss the peaches in a bowl with the lemon juice to prevent browning. Place the peaches in the bottom of a 9-by-13-inch baking dish and sprinkle with the cinnamon.
In a separate bowl, combine the flour, sugar, butter and pecans if using. Mix gently until well blended and crumbly. Crumble the topping evenly over the peaches--you should be able to see some of the fruit through the topping.
Bake until the peaches are tender, about 30 minutes.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.