Biscoff Spread: I use anywhere from ¼ to ⅓ cup of slightly warmed biscoff spread, but you can use more or less if you want. For 4 cups of heavy cream, I wouldn't add less than ¼ of a cup. It's entirely up to you and how much you want to taste the biscoff spread in the filling. Remember, you still add biscoff drizzle between the layers.