In a large bowl, whisk the cocoa powder, sugar, oil, applesauce, and vanilla extract for 1 minute.
In a small bowl, whisk the flour, cinnamon, baking powder, baking soda, and salt.
Add the dry ingredients to the wet ingredients and mix until just combined.
Cover the bowl with plastic wrap and refrigerate for at least 5 hours or overnight.
When ready to bake, preheat the oven to 350 degrees F (175 degrees C) and line a baking sheet with a silicone mat or parchment paper. Put the powdered sugar in a small bowl.
Scoop 2 Tablespoons of dough into your hand and roll it into a ball.
Roll the ball in the powdered sugar until it is heavily coated. Add more powdered sugar to the bowl if it runs out.
Place the ball on the baking sheet, keeping the powdered sugar in place. Repeat with the remaining dough, spacing the cookies 2 inches apart.
Bake for 10 minutes, until the edges are set and the centers are still slightly soft.
Set the baking sheet on a wire rack and let the cookies cool for 10 minutes. Then carefully move them to the rack to cool completely, at least 1 hour.
Notes
Use a good-quality unsweetened cocoa powder for the richest chocolate flavor.
Don't skip the chill. It keeps the cookies from spreading too much and helps create the crackled tops.
For a more dramatic crinkle, roll the dough balls in sugar first, then in the powdered sugar.
Mix the dough until just combined, since overmixing can make the cookies tough.
Store cooled cookies in an airtight container at room temperature for 2 to 3 days or in the fridge for 5 to 7 days, or freeze them for 2 to 3 months.