- Preheat your oven to 350° and line two baking trays with parchment paper. (Never skip your parchement paper!) 
- In a medium bowl, sift together the flour, salt, and baking powder. Set aside.  
- In a sauce pan, or in short bursts in the microwave, melt together the chocolate, espresso powder (if using) and butter.  
- With an electric mixer, whip together the eggs and sugar until pale yellow and very fluffy. At least 3 minute. If the color hasn't changed, it hasn't gone long enough.  
- Turn off the mixer, add in vanilla extract. Next, with a spatula, slowly mix the chocolate mixture into the eggs and sugar. Mix until just combined.  
- With a cookie scoop, or spoons, portion out roughly 2-3 tablespoons of the cookie dough.  
- Baker for 10-12 minutes until slightly domed. Cookies will fall and crackle more as they cool. Sprinkle with course salt, optional.