Preheat oven to 300 degrees. Line a quarter baking sheet with parchment paper. Lay 24 Biscoff cookies lengthwise in pan, logo side down; set aside.
In a small saucepan, heat butter and brown sugar on medium heat until it comes to a low simmer. Cook, stirring constantly, for 4 minutes. Pour the butter mixture over the Biscoff cookies and spread evenly using a spatula.
Place the cookies in the oven for 8 minutes. Remove from oven and immediately sprinkle the top with chocolate chips. Let sit for 2-3 minutes to warm the chocolate, then spread the chocolate overtop using a spatula or butter knife. Sprinkle on a pinch of sea salt and leftover crushed Biscoff cookies.
Let the cookies sit until the chocolate has completely hardened. Then, lift the cookies off the pan and break into pieces.
Notes
This recipe is intended to be made on a quarter sheet baking pan. If you don't have one, you can use a lined 9 x 13 inch baking pan.
You can double this recipe and make it on a half sheet pan. Be sure to buy two packages of Biscoff cookies instead of one.
When cooking the toffee, be sure to stir constantly for the full four minutes so that the toffee doesn't burn or stick.
This recipe calls for semi sweet chocolate chips, but you can substitute milk chocolate or dark chocolate.
Biscoff Toffee is a sweet treat so I like to sprinkle on sea salt to balance out the flavors.
Store leftovers in an airtight container in the refrigerator for up to a week.