Adjust oven rack to middle position and heat oven to 375°. Line 2 baking sheets with parchment paper; set aside. Sift flour, salt, and baking soda onto large sheet of parchment paper; set aside.
In bowl of standing mixer fitted with paddle attachment, beat melted butter, granulated sugar, brown sugar, and corn syrup at low speed until thoroughly blended, about 1 minute. Add yolk, milk, and vanilla; mix until fully incorporated and smooth, about 1 minute, scraping bottom and sides of bowl with rubber spatula as necessary. With mixer running on low speed, fold up 3 edges of parchment around dry ingredients to form a pouch and slowly shake dry ingredients into bowl; mix on low speed until just combined, about 2 minutes. Do not overbeat. Add chips and mix on low speed until distributed evenly throughout batter, about 5 seconds.
Leaving about 2 inches between each ball, scoop dough onto parchment-lined baking sheets with 1¼-inch (about 1 tablespoon capacity) ice cream scoop. Bake 1 sheet at a time, until cookies are deep golden brown and flat, about 12 minutes.
Cool cookies on baking sheet 3 minutes. Using wide metal spatula, transfer cookies to wire rack and let sit until crisped and cooled to room temperature. (Can be stored in airtight container for up to 1 week.)
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