Line baking sheets with wax or parchment paper. Set aside.
Place the oats and hazelnuts in a medium-size mixing bowl. Set aside.
Combine the condensed milk and chocolate chips in a saucepan and cook over low heat, stirring constantly, until the chocolate is completely melted. Remove the pan from the heat, add the chocolate hazelnut spread and vanilla, and stir until completely incorporated. Add the oats and hazelnuts to the chocolate mixture and mix until the oats are fully coated with chocolate.
Drop the mixture (2 Tbsp for each cookie) onto the lined baking sheets. Let the cookies set until cooled and hardened.