Preheat oven to 375 degrees F. In a large bowl, beat butter with an electric mixer on medium to high speed for 30 seconds. Add granulated sugar, brown sugar, baking soda, cream of tartar, and salt. Beat until combined, scraping bowl occasionally. Beat in egg, milk, and coconut extract until combined. Beat in as much of the flour as you can with the mixer. Stir in any remaining flour with a spatula or wooden spoon.
Shape 2 level measuring tablespoons of dough into a 12-inch rope. Cut rope crosswise into three 4-inch pieces. Brings ends of each piece together to form a ring. Arrange rings 2 inches apart on ungreased baking sheets. Repeat with remaining dough.
Bake for 6 to 7 minutes or until edges are firm but not brown. Transfer to a wire rack; cool. Dip each cookie in Dark Chocolate Glaze and sprinkle with coconut. Let stand until glaze is set.
Enjoy immediately, store in an airtight container at room temperature for 2 days, or freeze for up to 3 months.
In a medium saucepan, heat and stir Ghirardelli 60% Cacao Bittersweet Chocolate Baking Chips and butter over very low heat until melted and smooth. Remove from heat. Stir in powdered sugar, corn syrup, and vanilla. Stir in hot water to make a thin glaze. If necessary, as glaze stands, stir in additional hot water to reach original consistency.