In a small/medium bowl place the butter, sugar, condensed milk and vanilla
Cream until light and fluffy, I use my cake mixer, but an electric beater or a wooden spoon and some elbow grease will work just fine.
Add the flour, baking powder, and oats (I don't sift but I do attempt to sprinkle the baking powder into the mixture relatively evenly)
Create the condensed milk cookie dough by incorporating the dry ingredients, I use a beater on a low speed.
Add the chocolate, and mix until it is relatively evenly distributed, I use a wooden spoon to do this (only because this is what my mum did). You can use your mixer on low speed.
Take tablespoons of the dough and roll into balls (you should end up with approximately 24 balls, depending on how many are gobbled up during the process)
Place the balls on a baking paper lined baking tray
Take a fork and gently press each ball (kids love this task)
Bake at 180 degrees Celsius, which is approximately 360 Fahrenheit, for 15 minutes