Grease an 8x8 pan with the 1 tbsp of coconut oil.
Add 3.5 cups of rice puffs to a food processor. Pulse a few times to break the puffs into small pieces. You don't want the puffs to be too fine. But I found when making these smaller pieces are better. Pulse for 10 seconds 2-3 times.
Add the puffs, nut butter, sweetener, vanilla, and chia seeds to a bowl. Mix thoroughly until the mixture sticks together. You may need to use your hands to fully incorporate the mixture.
Pour the puff mixture into your greased pan. Using the back of a metal spoon or a metal measuring cup and your hands, press firmly down of the mixture. Place in the freezer for 1 hour.
Prepare the chocolate drizzle with 10 minutes left in the freezing time.
Add the coconut oil and the chocolate to a saucepan and place over low heat. Stir while the chocolate melts. Take the puff squares out of the freezer. Remove from the pan and cut into 9 squares. Place the squares on a cooling rack with a piece of parchment paper underneath to catch excess chocolate. Using a spoon, drizzle the chocolate over the squares. Place back in the freezer for at least 15 minutes.
Store the rice crispy treats in the freezer.