Preheat oven to 325 degrees F. Line 2 baking sheets with silicone liners, or mist baking sheets lightly with cooking spray and set aside.

In the bowl of a stand mixer, beat together the butter, brown sugar, and white sugar with the paddle attachment until creamy, about 2 minutes. Add in the eggs and vanilla until incorporated. Lastly, add in the baking soda, baking powder, milk powder, salt, and flour until a soft dough forms. Stir in the oats, cornflakes cereal and coconut by hand, (and if using chips, stir those in now, too).

Drop rounded, Tablespoon-sized balls of dough onto the baking sheets, keeping about 2" apart. Bake for approx. 10-12 minutes, rotating pans halfway through baking time to ensure even cooking. Cookies are done when the edges are light golden brown. The cookies may appear slightly undone; this is okay - just do not over bake. Allow the cookies to cool for about 15 minutes on the sheets before transferring carefully to a wire rack to cool completely.

Store cookies airtight, at room temperature, up to a week. Cookies are best served warm or at room temperature.