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Melt the chocolate in a double boiler and set aside to cool.
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In a separate bowl, whisk together the flour, baking soda, baking powder, and 1/4 teaspoon of salt. Set aside.
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Switching to a stand mixer or hand mixer, beat the butter with the espresso powder until creamy. Scrape the sides and bottom of the bowl, and then add 1 cup of sugar. Beat on medium speed for about 3 minutes, until light and fluffy.
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Beat in the vanilla, then the eggs, one at a time, and scraping the sides and bottom of the bowl as you go.
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Beat in the melted chocolate at medium low speed. Scrape the sides and bottom of the bowl.
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Mix in the flour mixture on the lowest speed. When it is completely incorporated, cover with plastic wrap and let chill for 30-60 minutes.
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When you are ready to bake, preheat the oven to 350 F.
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Whisk together the remaining 1/4 cup granulated sugar with the remaining 1/2 teaspoon of fine sea salt.
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Scoop out 1-inch balls of cookie dough, and then roll them into a ball, and then roll in the sugar-salt mixture. Place on a parchment or silicone mat-lined cookie sheet, 2 inches apart (I got 20 to a sheet). Bake for 9-12 minutes, or until the tops have cracked but the centers are still a little soft. Let cool on the cookie sheet for 3-5 minutes, and then transfer to a cooling rack.