Take a bowl, mix peanut butter and egg, beat unsalted butter until creamy for 2 minutes, add brown sugar and white sugar, beat for another 2 minutes. Pour this mixture in the bowl and mix well.
In another bowl, vigorously whisk flour, baking soda, baking powder and salt. Stir the dry ingredients into the sugar butter mixture.
Wrap dough in plastic and refrigerate for at least 3 hours.
Reheat the oven to 375°F (190°C).
Shape the cookies
Shape the dough into 1 1/4 inch balls. Place the balls of dough about 3 inches apart on ungreased cookie sheets (unlined sheets are fine, though you can use parchment paper to line them, if you like). Flatten in a crisscross pattern with a fork (It helps to dip the fork in sugar to keep it from sticking to the dough)
Bake the cookies:
Bake one sheet at a time on the centre rack at 375°F (190°C) until light brown for 9 to 11 minutes.
Remove the cookies from the oven and let them cool in their baking sheets for a minute.
After 1 minute, transfer the cookies to a rack to cool completely.
Melt dark chocolate, pour it in a heart shaped mould and keep it in cool area.
When cookies are baked, put heart shape chocolate on top and enjoy the crunchy chocolaty taste.
