Preheat the oven to 350°F (177°C).

Wash, peel, and slice 5 ripe peaches into thin slices. (This equals about 4 cups of sliced peaches.)

In a large mixing bowl, combine peaches, granulated sugar, lemon juice, and salt. Toss gently.

Add tapioca flour (or arrowroot starch), cinnamon, and kosher salt, and mix until peaches are evenly coated.

Stir in coconut sugar and maple syrup for extra depth of flavor. Set aside.

In a separate mixing bowl, combine flour, hazelnut meal, and brown sugar.

Cut in cold butter using a pastry cutter or fork until the mixture becomes crumbly.

Stir in lemon juice, and optionally add cinnamon, nutmeg, and chopped nuts for extra flavor.

Transfer the prepared peach filling into a greased 8 x 8-inch baking dish.

Evenly sprinkle the crumble topping over the peaches, ensuring full coverage.

Place the dish in the preheated oven and bake for 45–50 minutes, or until the topping is golden brown and the peaches are bubbling.

Remove from the oven and allow to cool for at least 30 minutes before serving.