Preheat the oven to 350°F (175°C). In a mixing bowl, combine sliced peaches, sugar, and lemon juice. Mix well and spread evenly in the bottom of a greased 9x13 inch baking dish.

Sprinkle the dry yellow cake mix evenly over the peach mixture.

Drizzle the melted butter over the cake mix. If using, sprinkle chopped pecans on top.

Bake in the preheated oven for 45 minutes, or until the top is golden brown and the peaches are bubbly.

Let cool slightly before serving. Serve warm, optionally with vanilla ice cream.