In a medium bowl, whisk together flour, cocoa, and salt. Set aside.
In a medium bowl, whisk together flour, cocoa, and salt. Set aside.
With a stand mixer (or hand mixer), beat butter and sugar on medium speed until light and fluffy, about 2 minutes.
Add egg yolk, milk, and vanilla and mix until combined, one more minute. Scrape down sides of the bowl if necessary.
Scrape down sides of the bowl if necessary. Reduce speed to low and slowly add flour mixture until just combined.
Wrap dough in plastic wrap and refrigerate until firm, 1 hour. Preheat oven to 350°F.
Place egg whites in one small bowl and chopped pecans in a separate small bowl. Roll chilled dough into 1-inch balls, dip in egg whites,
Then roll in pecans. Place balls about 2 inches apart on prepared baking sheet.
Using a 1/2 teaspoon measuring spoon, make an indentation in the center of each dough ball. Bake until set, about 12 minutes.
Once cookies are removed from the oven, gently re-press the indentations. Prepare the caramel. Fill the indentions with ½ teaspoon of caramel.
Drizzle with chocolate and enjoy!