Step 1

In a large mixing bowl, beat together butter and powdered sugar until fluffy and light. Beat in vanilla.

Step 2

In a small bowl, combine flour, cocoa powder, and salt. Add gradually to butter mixture, beating all the while until incorporated completely.

Step 3

Fold in both chocolate chips.

Step 4

Shape dough into two 2-inch diameter logs. Wrap each log tightly in cling wrap and place in freezer for 45 minutes.

Step 5

Preheat oven to 350 degrees F. Lightly grease a baking pan and set aside.

Step 6

Remove dough from freezer and unwrap cling wrap. Cut dough into 1/4-inch thick rounds and.place each round one inch apart on prepared baking sheet.

Step 7

Bake in preheated oven for 10-12 minutes, until set. Cool completely, then enjoy!