Preheat the oven to 350F (180C). Grease a 12×16 inch (30x40cm) baking sheet an line with parchment paper.
In a medium bowl sieve and whisk flour with cocoa powder, baking powder and salt. Set aside.
In a large bowl add eggs, vanilla and sugar.
Beat with an electric mixer until lemon yellow and foamy.
Add oil and mix until well incorporated.
Gradually fold in the flour mixture.
Pour the mixture into the prepared pan.
Bake for about 8-10 minutes until a toothpick inserted into the center comes out clean.
Sprinkle with powdered sugar. This helps the cake not stick. Flip the cake over a kitchen towel. Remove the parchment paper it was baked with.
Roll with the kitchen towel inside. You will have to do it while is still hot/warm otherwise it cracks. Let cool completely.