Line your countertop or several baking sheets with parchment paper.
Add cornflakes to a large bowl.
In a medium pan add the corn syrup and sugar and heat over medium heat until sugar dissolves.
Once dissolved, remove from heat and stir in the peanut butter and vanilla until combined and smooth.
Pour mixture over the cornflakes and stir gently until all the corn flakes are coated.
Using a medium size cookie scoop, drop heaping scoops onto the parchment paper. Let cookies cool for about 30 minutes to set up.
Once they are set, mix together the vegetable or coconut oil with the chocolate chips in a small bowl. Microwave in 30 second intervals, stirring in-between, until chocolate is melted.
Place chocolate in a small piping bag and cut the tip off and drizzle over cookies (or use a ziploc bag and cut the tip off). Let chocolate sit for about 15 minutes to set up.
Notes
These can be frozen, see how to do that above.
Other cereals can be used like Rice Krispies, Chex or Crispix cereal.