Grease and lightly flour 11 x 7 pan (or 13x9 pan if you do not have 11x7) and set aside
In small saucepan, heat ⅔ cup water until it just begins to boil. Add cocoa powder, semisweet chocolate, and instant coffee. Immediately remove from heat and stir constantly until mixture is smooth and silky.
In large microwave-safe bowl, melt butter on 15 second increments, stirring at intervals until completely melted.
Stir in sugar and vanilla.
Stir in chocolate mixture, stirring until completely combined.
Add eggs and egg yolks, stirring until completely combined.
Sprinkle salt over batter and stir in.
Gradually stir in flour until completely combined.
Spread batter into prepared pan and bake on 350F for 30-35 minutes if using 11x7 pan and 25-30 if using 13x9 pan (time may vary depending on your individual oven. To check if brownies are done, insert a toothpick into the center of the pan. If it comes up wet with unbaked batter return it to the oven and continue to check every five minutes. When the brownies are completely done, the toothpick will be slightly fudgy and may have a few crumbs, but it will be a a fudge-like consistency and not a wet batter consistency.