Step 1

Preheat oven to 350 F; line two baking sheets with parchment paper.

Step 2

In the bowl of an electric mixer fitted with the paddle attachment, beat together the butter, sugar, salt, and vanilla extract on medium-high speed until smooth, about 2 minutes. Beat in flour, beginning on low speed and increasing to medium-high, until a dough forms.

Step 3

Roll dough into 12 equal size balls, about 1 1/2 tablespoons of dough, placing 6 on each cookie sheet.

Step 4

Bake for 10 minutes, removing from oven and using a ½ tablespoon measuring spoon make an indentation in the middle of each cookie. Return to oven and bake for another 1-2 minutes. Remove to a wire rack to cool.

Step 5

When cookies are cool, make the fudge filling. Place the chocolate chips and sweetened condensed milk in a bowl and microwave for 20 seconds. Mix until smooth. (If not melted completely microwave 10 seconds at a time, stirring in-between until smooth.)

Step 6

Use a small spoon to fill the thumbprints with the fudge. Top with desired toppings. Let cool and enjoy!