Adjust oven rack to middle lower position. Preheat oven to 350°F.
Line a 9x13 inch pan with foil, leaving a 1-2 inch overhang on all sides so that you can easily remove the brownies. Spray the foil with nonstick cooking spray.
In a large bowl whisk the boiling water and cocoa powder until smooth. Add the unsweetened chocolate and whisk until the chocolate is melted. Next, whisk in the butter and oil. (Mixture might look clumpy and curdled).
Whisk in the eggs, egg yolks, and vanilla, stirring until smooth.
Whisk in the sugar until thoroughly combined. Using a spatula fold in the flour, salt, and chocolate chips. Do not overmix.
Transfer the batter to the prepared pan and bake for 30-35 minutes or until a toothpick inserted in the center comes out with a few moist crumbs. Be careful not to overbake as that makes brownies dry.
Remove pan from the oven and place on a wire rack to cool completely. (about 1 ½ hours).
When ready to slice and serve remove the foil liner, lifting the brownies out of the pan. Cut serve!