Combine butter, sugar, and vanilla over low heat until melted.

Add chocolate chips and stir until partly melted.

Remove from heat and stir until smooth. Let cool for 10 minutes.

Combine flour, salt, and baking soda in a separate bowl.

Beat eggs into the chocolate mixture one at a time on medium speed.

Reduce mixer to low speed and add the flour mixture. Beat until just combined.

Mix in mint chips (if using).

Chill dough for 1 hour.

Preheat oven to 350°F.

Roll dough into balls and place on parchment paper-lined baking sheets, 2 inches apart.

Bake for 10 minutes.

Place an Andes Mint half on top of each cookie.

Return to the oven for 60 seconds to melt the mint slightly.

Remove from the oven and spread mint around with a spoon.

Let cool on a wire rack.