Makes 1 1/2 dozen 3-inch cookies
2 1/8 cups unsifted bleached all-purpose flour (2 cups plus
1/2 teaspoon salt
1/2 teaspoon baking soda
8 tablespoons unsalted butter (1 1/2 sticks), melted and cooled until warm
3/4 cup brown sugar (light or dark)
1/2 cup granulated sugar
1/2 cup Nutella
1 large egg
1 additional egg yolk
2 teaspoons vanilla extract
1 to 2 cups semi- or bittersweet chocolate chips/chunks
1 cup chopped walnuts or pecans (optional)
Heat oven to 325 degrees F. Line a 20 x 14-inch baking sheet (without sides) with parchment paper.
Mix flour, salt, and baking soda together in medium bowl. Set aside.
With electric mixer, mix butter and sugars until thoroughly blended. Mix in Nutella, egg, yolk, and vanilla extract. Add dry ingredients; mix until just combined. Stir in chips to taste.
Form scant 1/4 cup dough into ball. Holding dough ball using fingertips of both hands, pull into two equal halves. Rotate halves ninety degrees and, with jagged surfaces exposed, join halves together at their base, again forming a single cookie, being careful not to smooth dough's uneven surface. Place formed dough onto prepared cookie sheet - about nine dough balls per sheet. Smaller cookie sheets can be used, but fewer cookies can be baked at one time and baking time may need to be adjusted. (Dough can be refrigerated up to 2 days or frozen up to 1 month - shaped or not.)
Bake until cookies are light golden brown and outer edges start to harden, yet centers are still soft and puffy, 15 to 18 minutes (start checking at 13 minutes.) (Frozen dough requires an extra 1 to 2 minutes baking time.) Cool cookies on cookie sheets. Serve or store in airtight container.