Take a big bowl and sift the flour, salt and baking powder. Then mix it all together once to combine it well.
In a mixing bowl add the granular sugar and oil and mix / beat it together using the paddle attachment / mixer attachment. Scrape the bowl in between and beat again.
Scrape the bowl down and add cocoa powder. Beat it together until well combined, scrapping it at regular intervals. If you are using espresso powder then this is a good time to add it.
Add eggs and vanilla extract and mix it together.
Add the all purpose flour to the mixture and mix it well scraping in between till everything is well combined.
Either transfer the dough to an air tight container or cover it bowl with a tight cling wrap and refrigerate it overnight.
Pre-heat the oven at 350F and line the baking tray with parchment / baking paper.
Roll the chilled dough into small bowls using the small ice cream or cookie scoop or a table spoon.
Roll all the balls in the powdered sugar.
Place the sugar covered ball on a parchment lined baking tray about 2 inch distance from each other.
Bake for 10 to 12 mins. The cookies will rise and develop some beautiful cracks.
The hot cookies will be too soft and easily breakable. Let them cool for an hour and they will change the texture.
Once cooled the outside of the cookie will be slightly crisp and the inside would be soft and fudgy.
Notes
Always measure your ingredients correctly. Do not hard press the flour in the measuring cup. This will lead to extra flour and denser cookies.
Let the dough refrigerate for at least 8 - 12 hrs.