Preheat the oven to 350F. Line two baking sheets and set aside.

In a large dish combine flour, cornstarch, salt and baking powder. Set aside.

In a separate dish put butter and sugar and mix well using electric mixer, medium speed, until it gets light and fluffy. Add an egg and vanilla and mix until combined.

Continue mixing slowly adding dry ingredients. The dough will be crumbly. Knead it well with your hands. Put some flour on the table and place the dough on it.

Roll the dough up to ¼ inch thick. Cut it in round shapes. I used a glass 2.4 inch in diameter. Place the cookies in the baking sheets.

They should be 2 inches apart. Put them in the oven and bake for 8-9 min. Take them out of the oven and leave to cool for a couple of minutes on the baking sheets.

Transfer them to a wire rack to cool completely.

In medium dish mix butter, cream cheese and vanilla, with a hand mixer, medium speed. Add powdered sugar and mix until well combined.

Divide the mixture into 3 bowls. Add red food color in the first one, slowly, until you get the shade that you like. Put green in the second bowl, and leave the third one white.

Spread the filling evenly on the cooled cookies and sprinkle with crumbs.