Line 2 baking pans with parchment paper, ensuring the paper lies flat and covers the base completely.
With an electric hand mixer, cream the room temperature butter and granulated sugar for 2–3 minutes until pale, light, and fluffy, scraping down the sides of the bowl as needed.
Mix in the oil, egg, and vanilla extract, whipping for about 1 minute until smooth and fully combined, scraping down the bowl if needed.
Whisk together the flour, cocoa powder, salt, and baking soda, then add to the wet ingredients. Gently fold with a rubber spatula until just combined, without overmixing.
Scoop the cookie dough into the baking sheets - it will be about 15-16 balls using a cookie or ice cream scooper that holds about one tablespoon. Let the dough rest in the refrigerator for about an hour.
Coat the cookies
Preheat the oven to 330°F (165°C), no fan.
Place the granulated sugar onto a plate and the powdered sugar onto a separate large plate. Roll the dough balls first in granulated sugar, then in powdered sugar. Make sure the powdered sugar is very generous; coat the entire cookie dough ball with a thick layer. Place the coated cookie balls on the baking sheets, leaving enough space between them to be able to spread
Bake
Bake the cookies for at 165 C / 330°F (no fan) for about 15 minutes.
After baking, let the cookies rest for a few minutes, then carefully transfer them to a cooling rack to cool. The cookies will further set as they cool.
Storage
Room temperature: Store in an airtight container for up to 4-5 days.Fridge: Store in an airtight container for up to 5–7 days. Bring to room temperature before serving.Freezer (baked): Freeze in an airtight container for up to 2 months. Thaw at room temperature.Freezer (dough): Freeze dough balls (uncoated) up to 2 months. Thaw slightly, coat in powdered sugar, then bake.
Notes
INGREDIENT NOTES:
Measure all ingredients using a digital scale for the most accurate results.
Use room-temperature ingredients (especially eggs and butter) for a smoother batter and better emulsification.
Use only unsweetened Dutch-processed cocoa powder for a deeper chocolate flavor and better color.
TECHNIQUE NOTES:
Make sure you read my Expert Tips section above to maximize your success. A short recipe alone cannot cover all the necessary details and science behind baking.
Do not overmix the dough when adding the dry ingredients. Only fold it until thoroughly combined.
Respect the chilling time in the cookie recipe; this is a very wet dough, and chilling allows the butter to firm up. Do not skip this step, or the cookies may spread too much and turn out very flat.
If you prefer your crinkle cookies fudgy and gooey, try not to overbake them. In my oven, they took about 15 minutes to bake. However, each oven is different, so it might take shorter or longer.
Do not immediately remove the cookies from the baking sheet after baking, as they will continue to set as they cool and may break if moved too soon.