Line the bottom and all sides of an 8 1/2 × 4 1/2-inch loaf pan with plastic wrap, leaving about 6 inches of overhang on two sides.
In a stand mixer fitted with the whisk (or in a large bowl with a hand mixer), beat together the cream cheese and powdered sugar on medium speed until the mixture is light and creamy, about 1 minute. Add the heavy cream, sour cream, cookie butter, vanilla, and salt and beat on low speed until combined. Increase the speed to medium-high and beat the mixture until medium peaks form, 30 seconds to 1 minute.
Spread 1 1/4 cups of the whipped cream mixture across the bottom of the prepared pan. Arrange a single layer of cookies over the top, making sure to really pack them in there and minimize the gaps between the cookies. If necessary, break some of the cookies to fit them properly. Gently press the cookies into the cream.
Use a spatula to evenly spread another 1 cup of the whipped cream mixture over the cookies. Arrange another layer of cookies on top, pressing them gently into the cream. Repeat this once more, finishing with the layer of cookies. You may have a few leftover cookies.
Use the overhanging plastic wrap to cover the loaf and transfer the pan to the refrigerator. Chill for at least 8 hours or (preferably) overnight to set.
Unfold the plastic wrap from the top of the loaf and carefully invert the pan onto a serving plate. Remove and discard the plastic wrap.
Slice the loaf into eight 1-inch slices and serve garnished with crushed Biscoff cookies.
OPTION: Melt Biscoff spread in the microwave for 20 to 30 seconds, just until runny, and drizzle over inverted icebox cake.