Whisk together egg and sugar in a bowl to a fluffy mass
Chop the butter (do not melt it, since it will ruin the texture of the cookies) and add it to the fluffy mass. Whisk (preferably with an electric beater) thoroughly. If you take a spoon and taste it, you should not be able to taste clumps of butter (but you might still be able to see them).
Add the peanutbutter and vanilla to the dough.
Add the baking powder and salt as well
Mix baking powder, salt, flour, and coconut
Combine the flour-mixture and the sugar-mixture till it has an even consistency
Chop the white chocolate and add it to the dough
Form balls at the size of tennis balls and put them on a sheet of baking paper on a baking pan. Sqezze the balls flat either with your hand or a table spoon with some flour on the back of it (so that it doesn't stick to the cookies)