Add the oil and both sugars to a medium bowl and with a sturdy spoon beat till nicely combined.
Mix in the egg and vanilla extract, and beat with the spoon.
Sift in the flour and baking powder and mix until well incorporated.
Lastly add in the chopped chocolate and nuts making sure that they are well distributed into the mixture.
Using 2 teaspoons, make piles of two teaspoons big on a baking sheet, while making sure to leave enough room between the cookies. You should be able to make 15 to 20 cookies depending on your spoon size.
Bake in a preheated oven for 8 to 10 minutes, or until cooked on the sides and slightly doughy in the middle.
Notes
Instead of using white chocolate and walnut pieces, you can also opt for the same amount of these combinations:
Milk chocolate and hazelnuts
Dark chocolate and almonds
Or any type of chocolate with any kind of nut of your choice
A mixture of white, milk, and dark chocolate
Oats and raisins
Oats and nuts
Fudge pieces, possibly with chocolate
Any kind of fruit
While baking they will inflate but after cooling they will deflate again, it's marvelous to watch.