Preheat your oven to 350°F (175°C). Peel, pit, and slice the peaches into a large bowl. Mix in the granulated sugar and lemon juice until well combined. Spread the peach mixture evenly into your baking dish.
In a separate bowl, combine the flour, rolled oats, brown sugar, and ground cinnamon. Cut in the cold butter using a pastry cutter or fork until the mixture resembles coarse crumbs. Stir in the chopped almonds.
Sprinkle the crumble topping evenly over the peaches, covering the fruit completely.
Place the assembled dish in the preheated oven and bake for about 40 minutes, or until the topping is golden brown and the peach filling is bubbling around the edges.
Remove the peach crumble from the oven and let it cool slightly. Serve warm, ideally with a scoop of vanilla ice cream or a dollop of whipped cream if desired.