Preheat your oven to 350℉. Line baking sheets with parchment paper and set aside.
In a large mixing bowl, cream the butter, granulated sugar, and brown sugar until the mixture is light and fluffy, about 3 minutes.
Add the eggs and vanilla and beat until fully incorporated.
In a separate bowl, whisk together the flour, oats, baking soda, and salt.
With the mixer on low speed, gradually add the flour mixture to the wet ingredients, mixing until just combined.
Stir in the semi-sweet chocolate chips, sweetened coconut flakes, cornflakes, and rice krispies cereal until evenly distributed.
Using a 2 tablespoon cookie scoop, drop dough onto lined baking sheet with 2 inches inbetween each cookie.
Bake the cookies in the preheated oven for 10-13 minutes. The cookies should be set on the edges but will look soft and slightly underdone in the center. Do not overcook. They will continue cooking on the baking sheet.
Remove the cookies from the oven and allow them to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.
Notes
The key to these cookies is to bake until they are just set. They will look undercooked, but as long as the edges are set, they will continue to bake on the baking sheet and you will end up with the ideal texture- soft and chewy on the inside with a crunchy exterior. Store in an airtight container at room temperature for up to 1 week.