Preheat oven to 400F
Cream together butters and sugars until creamy (about 2 mins)
Add in egg and vanilla and mix until combined.
In a separate bowl mix together flour, corn starch and baking soda.
Slowly add in flour mix to wet ingredients and stir until thoroughly combined.
Roll dough into 1 in balls.
Place REESE'S Mini on top of one ball and place another ball on top.
Roll the two balls together, with REESE'S Mini in middle and then flatten.
Place on greased cookie sheet and bake for 10-15 minutes until golden brown on top.
Let cookies cool on cooling rack.