Step 1

Preheat oven to 350°F (177°C). Line two 12 count muffin pan with liners. Set aside.

Step 2

In a large bowl using a hand-held mixer or stand mixer with paddle attachment, cream the butter and sugars together on medium speed until fluffy and light in color. Mix in egg and vanilla. Scrape down the sides as needed. In a separate bowl, combine flour, cornstarch, baking soda and salt. On low speed, slowly mix into the wet ingredients. Stir in chocolate chips. Dough will be thick.

Step 3

Press 1.5 Tablespoons of dough into each muffin liner. Bake for 12-13 minutes, removing from the oven when the edges begin to slightly brown and the centers still appear soft. Do not bake longer than 13 minutes. Allow cookie cups to cool completely before frosting.

Step 4

With an electric or stand mixer using a paddle attachment, cream together the butter and brown sugar at medium speed. Add the vanilla and beat well. Stir in the flour and salt until doughy. Beat in the milk until fluffy. Gently fold in chocolate chips. Frost cooled cookie cups.

Step 5

Unfrosted cookie cups stay fresh covered at room temperature for 5 days. Frosted cookie cups must be stored in the refrigerator.