Bakery Style Butter Cookies

From SmittenKitchen

INGREDIENTS
1 cup (2 sticks) unsalted butter, softened
2/3 cup granulated sugar
2 large egg yolks

1 teaspoon vanilla extract

1/2 teaspoon fine sea salt
2 cups flour

TO FINISH
1 cup semisweet chocolate chips

Sprinkles

DIRECTIONS

• Heat the oven to 350 degrees. Line two large baking sheets with parchment paper.
• Combine the butter and sugar until well blended and light. 
• Add the egg yolks, vanilla, and salt, and beat to combine. Scrape down the bowl and beaters. 
• Add the flour, and mix just until the flour disappears. 
• Fit a piping bag with a large French star tip - use a cloth or other thick type of piping bag since cookie dough will be thick (ziplock bag will break)
• Pipe the dough into about 1/2-inch-wide, 1 3/4-to-2-inch-long segments, spaced about 1 inch apart, on your baking sheets. 
• Bake the cookies for 11 to 13 minutes, or until they are golden at the edges.
• Cool completely on the baking trays, or for at least 2 minutes, to make them easier to lift to a cooling rack. 
• Melt chocolate chips in microwave in tall glass (makes it easier for dipping) on 50% power for a minute, stir, only put back in microwave for a short bit more (don't overheat them)
• Dip cookie into chocolate, or use knife to spread it on cookies
• Put sprinkles in shallow bowl and dip cookie into it

Do ahead: These keep at room temperature in an airtight container for a week.