Preheat the oven to 350°F. Grease a 9x13-inch baking dish.
In a large bowl, combine the sliced peaches and lemon juice. Sprinkle with ½ cup of granulated sugar and ½ teaspoon of cinnamon. Toss to coat the peaches evenly, then spread them in the prepared baking dish.
In another bowl, mix the oats, flour, brown sugar, melted butter, and remaining ½ teaspoon of cinnamon until crumbly. Sprinkle this mixture evenly over the peaches.
In a separate bowl, whisk together the heavy cream, milk, eggs, vanilla extract, remaining ½ cup of granulated sugar, and salt until well combined. Pour this mixture over the peach and oat layers in the baking dish.
Bake for 40-45 minutes, or until the top is golden brown and the pudding is set. Let it cool for about 10 minutes before serving.