To a large microwave-safe bowl, add the chocolate and heat on high power to melt, about 1 minute. Stop to check and stir. Heat in 10-second increments until chocolate can be stirred smooth. Set aside to cool, about 10 to 15 minutes.
Add the granulated sugar, oil, vanilla, and whisk to combine.
Add the eggs, optional espresso granules (enhances the chocolate flavor), and whisk to combine.
Add the flour, baking powder, salt, and stir until just combined; don’t overmix.
Cover bowl with plasticwrap and place in the fridge to chill for at least 4 hours, overnight is better. The dough is more like brownie batter than cookie dough and baking with unchilled dough absolutely will not work.
After dough has chilled, preheat oven to 350F, line a baking sheet with a Silpat or spray with cooking spray.
Using a 2-tablespoon cookie scoop or your hands, form approximately 15 equal-sized mounds of dough; don’t flatten.
Add confectioners’ sugar to a small bowl and dredge mounds very well thorough sugar before placing on baking sheet, spaced at least 2 inches apart (I bake 8 cookies per sheet).
Bake for about 10 minutes (for very soft cookies, longer for more well-done cookies), or until edges have set and tops are just set, even if slightly undercooked and soft-looking in the center; don’t overbake. Cookies firm up as they cool.
Allow cookies to cool on baking sheet for about 10 minutes before serving. I let them cool on the baking sheet and don’t use a rack.
Notes
Cookies will keep airtight at room temperature for up to 1 week or in the freezer for up to 6 months.
Alternatively, unbaked cookie dough can be stored in an airtight container in the refrigerator for up to 5 days, or in the freezer for up to 4 months, so consider baking only as many cookies as desired and save the remaining dough to be baked in the future when desired.