Prepare your flax egg by combining your ground flaxseed with 3 tablespoons of water. Allow sitting for 10 minutes, until a gel is formed.
Preheat the oven to 180C/350F. Line an 8 x 8-inch pan with parchment paper and set aside.
In a large mixing bowl, combine your dry ingredients and mix well. In a separate small bowl, combine your flax egg, almond butter, coconut milk, and vanilla extract and mix very well.
Combine your wet mixture into the dry mixture and mix well, until fully combined. Fold through your chocolate buttons/chocolate chips, reserving a few to top the cookie bars with.
Pour the cookie bar batter into the lined pan and spread out evenly. Top with extra chocolate chips and chocolate buttons and bake for 20-25 minutes, or until the edges are golden brown and a toothpick comes out the center 'just' clean.
Remove cookie bars from the oven and allow to cool in the pan completely, before slicing into bars.
For ultra gooey monster cookie bars, remove from the oven around the 20-minute mark. Keto Monster Cookie Bars can be stored at room temperature and will keep for 5 days, covered.Monster cookie bars can be stored in the fridge and will keep fresh for up to 7 days.Healthy Monster cookie bars are freezer friendly and will keep well frozen for up to 6 months.