Preheat your oven to 350°F (175°C). Lightly grease an 8x8-inch baking dish or similar-sized oven-safe dish.

In a large mixing bowl, combine the sliced peaches, maple syrup (or honey), vanilla extract, lemon juice, and arrowroot starch. Gently toss until the peaches are evenly coated. Pour the peach mixture into the prepared baking dish and spread it out evenly.

In a separate bowl, mix together the gluten-free rolled oats, almond flour, chopped nuts, coconut sugar, cinnamon, and salt. Add the melted coconut oil (or butter) and stir until the mixture is crumbly and well combined.

Sprinkle the oat topping evenly over the peaches in the baking dish, covering them completely.

Bake in the preheated oven for 35-40 minutes, or until the topping is golden brown and the peach filling is bubbling around the edges.

Remove the crisp from the oven and let it cool for about 10 minutes before serving. Serve warm, optionally with a scoop of vanilla ice cream or a dollop of whipped cream.