Here’s a simple way to prepare an edible chestnut:

1. First, preheat your oven to 400°F (200°C).
2. Next, use a sharp knife to carefully score the shell of each chestnut. Make a small “X” shape on the flat side of each chestnut, cutting through the outer shell and just into the inner skin.
3. Once you have scored all of the chestnuts, place them in a baking dish or on a baking sheet.
4. Bake the chestnuts in the preheated oven for 15-20 minutes, or until the shells have opened and the nuts inside are tender and fully cooked.
5. Remove the chestnuts from the oven and allow them to cool slightly.
6. Once the chestnuts are cool enough to handle, peel off the outer shell and the inner skin to reveal the tender, sweet nut inside.
7. Enjoy the chestnuts as a snack, or use them in a variety of sweet or savory dishes.

Note: You can also cook chestnuts on a stovetop in boiling water or over an open fire. However, roasting them in the oven is a quick and easy method that results in delicious, tender chestnuts.