These Turtle Cookies combine buttery shortbread, rich caramel, toasted pecans, and melted chocolate into a delicious treat reminiscent of classic turtle candies.
In a large bowl, use a hand or stand mixer with paddle attachment to cream the butter and sugars on medium-high speed for 1 minute until light and creamy. Add the pinch of kosher salt, egg yolks, and vanilla extract. Scrape down sides, then mix in cornstarch until smooth. Gradually add the flour on medium-low speed until mostly combined. Remove bowl and fold dough with spatula until fully blended.
Form dough into one large ball, slightly sticky but manageable. Split into two halves and roll each into a 7 ½ inch long log on a clean surface. Wrap each log in plastic wrap and refrigerate standing up for at least 2 hours or overnight.
When ready, preheat oven to 350°F (175°C) and line a large baking sheet with parchment paper.
Slice one dough log into 12 cookies about 1/4 inch thick, keeping the other log chilled until ready. Arrange cookies 1 inch apart on baking sheet. Press 5 pecan halves into each cookie in a star shape resembling turtle candies.
Bake cookies for 12-14 minutes until puffed and edges are set. Allow to cool on the pan for a couple of minutes before transferring to a wire rack. Pecans may be loose while warm but will adhere as cookies cool. Repeat with second log.
In a medium saucepan, melt butter over medium heat. Whisk in brown sugar, corn syrup, sweetened condensed milk, and salt. Cook while whisking occasionally until the mixture reaches 235°F (113°C) using a candy thermometer, about 8 minutes. Remove from heat and stir in vanilla. Let caramel rest for 10 minutes to thicken.
Using two spoons, dollop about 1 tablespoon of caramel onto each cooled cookie. Let sit for 10 minutes to set slightly.
Spoon about 1 teaspoon of melted semisweet chocolate chips onto each cookie, swirling decoratively. Sprinkle flaky sea salt over the top to finish. Serve and enjoy!