Position the oven rack on the second level (just above the center) and preheat the oven to 350ºF. Prepare two baking sheets by lining them with parchment paper or silicone mats. Set them aside.

In a medium bowl, combine the all-purpose flour, baking powder, and salt, and whisk them together. Set aside.

1 cup All-Purpose Flour, 1 teaspoon Baking Powder, ⅛ teaspoon Salt

With a hand mixer or a stand mixer fitted with the paddle attachment, beat the eggs, egg yolk, granulated sugar, vegetable oil, and vanilla extract on medium-high until the mixture is frothy and well combined.

2 Large Eggs, 1 Large Egg Yolk, 1 cup Granulated Sugar, 1 tablespoon Vegetable Oil, 1 teaspoon Vanilla Extract

In a small saucepan, melt the semi-sweet chocolate chips and unsalted butter over medium heat until smooth. Remove from heat, then stir in the unsweetened cocoa powder and espresso powder.

6 tablespoons Unsalted Butter, 1 cup Semi-Sweet Chocolate Chips, ¼ cup Unsweetened Cocoa Powder

Gradually add the melted chocolate mixture to the wet ingredients and mix until just incorporated.

Add the dry ingredients to the wet mixture, mixing on low speed until just combined. Alternatively, you can fold them in with a spatula. The batter will be thin but still scoopable.

Using a cookie scoop or two spoons, scoop 1 ½-tablespoon portions of dough onto the prepared baking sheets, spacing them about 1 ½ inches apart.

Sprinkle a pinch of sea salt flakes on top of each cookie. Bake at 350ºF for 8-10 minutes, or until the tops are shiny and crackled.

Sea Salt Flakes

Remove from the oven and, if desired, add extra chocolate chips on top. For perfectly round cookies, use a round cookie cutter to shape them immediately after baking while they’re still soft. You can find more tips in my blog post on shaping cookies.

Allow the cookies to cool on the baking sheets for about 5 minutes before transferring them to a cooling rack. They’re delicious when slightly warm! Use a spatula to move them as they will still be soft.

Store the cookies in an airtight container at room temperature for up to 2 days.