Get out and measure your ingredients.
Preheat your oven to 350 degrees.
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 the pan edge. Prepare with cooking spray.
Add cocoa to a large bowl. Whisk in boiling water and stir until dissolved.
Add sugar, oil, eggs and egg yolks, cooled melted butter, and vanilla. Whisk until blended.
Gently whisk in banana pudding mix, flour and salt until incorporated. Do not overmix.
Transfer batter to prepared pan. Bake until toothpick inserted in center comes out with few moist crumbs attached, 34 to 39 minutes long, rotating pan halfway through baking.
Transfer pan to wire rack and let it cool for 1½ hours. Using the excess foil around the edges, lift brownies out of the pan. Return brownies to wire rack and let it cool completely, about 1 hour.
Cut into 2-inch squares and serve. Enjoy every bite.