Preheat your oven to 350 degrees and gather your ingredients.
Make a foil sling for your 13 by 9-inch baking pan by folding 2 long sheets of aluminum foil.
Lay sheets of foil inside your pan perpendicular to each other, with extra foil hanging over edges of the pan. Push foil into pan corners and all the way up the sides of the pan. As smooth as possible leaning to pan edge. Prepare with cooking spray.
Add cocoa to large bowl and whisk in boiling water, stirring until dissolved.
Add sugar, oil, eggs and egg yolks, cooled melted butter, and vanilla. Whisk until blended.
Gently whisk in vanilla pudding mix, flour and salt until just incorporated. Do not overmix.
Pour into prepared pan.
Bake until toothpick inserted in center comes out with few moist crumbs attached, 34-39 minutes, rotating pan halfway through baking.
Transfer pan to wire rack and let cool for 1½ hours.
Using foil overhang, lift brownies out of pan. Return brownies to wire rack and let cool completely, about 1 hour.
Once cooled, dust with powdered sugar, if desired
Cut into 3-inch squares.
Serve and enjoy.