Arrange an oven rack in the middle position and preheatit 325°F. Coat an 8-inch metal baking pan lightly with a teaspoon of olive oil, then line the pan with parchment, making asling with edges hanging above all sides by 1 inch.
In a medium mixing bowl, add the granulated sugar, brown sugar, olive oil, eggs and yolk, and vanilla extract. Stir vigorously to combine.
1/2 cup extra virgin olive oil, 1 cup granulated sugar, 1/2 cup packed light brown sugar, 1 tablespoon pure vanilla extract, 2 large eggs, 1 large egg yolk
In another smaller mixing bowl, whisk the flour, cocoa powder, espresso powder, and fine sea salt. Add to the sugar mixture and stir to combine. Stir in the chocolate chips.
1 cup plus 2 tablespoons unbleached, all-purpose flour, 2/3 cup Dutch process cocoa powder, 1 tablespoon instant espresso powder, 1/2 teaspoon fine sea salt, 1/2 cup dark chocolate chips
Bake for 30 minutes or until a toothpick inserted in the center comes out with a few moist crumbs at the tip.
Remove the pan from the oven and immediately sprinkle the flakey sea salt evenly over the top of the brownies. Cool in the pan for 10 minutes. Use the parchment sling to lift the entire brownie block from the pan.
2 teaspoons flakey sea salt
Allow the brownies to cool completely to ensure they cut cleanly, at least 1 hour. The longer the brownies cool, the more cleanly they will cut. Cut into 16 pieces, cutting 4 rows (3 cuts) in each direction. Store the brownies in an airtight container at room temperature for up to 4 days.