Best Homemade Cookies ever

Ingredients
125 g of butter
2 tosp of glass sugar
2 tosp of cocoa
2 tosp of cornstarch leggs + 1 egg yolk
1 tsp Vanilla
1 tsp of baking powder
2 cups of flour
1 top of chocolate for coating
For decoration:
200 g of chocolate
3 tosp of Roasted and coarsely chopped peanuts
2