Add the butter and Biscoff spread to the bowl of a stand mixer fitted with a whisk attachment (or use a large bowl and a hand mixer) and whip on high speed for 2-3 minutes, until light and airy.
Turn the speed to medium low and gradually add the sifted powdered sugar, a tablespoon at a time, until fully incorporated.
Lastly mix in the cream, vanilla extract, cinnamon and salt.
Turn the speed up to high and whip for 3 - 4 minutes until light and fluffy in texture.
You can use it right away or store in an airtight container in the refrigerator for up to 1 week. For longer storage freeze for up to two months. Bring up to room temperature on the counter and re-whip briefly before frosting.