Preheat oven to 350°F. Grease a 9-inch springform pan.
cookie crumbs, cookie butter, melted butter, brown sugar, and salt. Press firmly into pan (slightly up sides). Bake 10 min. Cool.
Bring cream cheese, eggs, sour cream, and cookie butter to room temp (1–2 hours) for a smooth batter.
Beat cream cheese until completely smooth, scraping bowl often.
Add sugar gradually, then mix in cookie butter until creamy.
Add eggs one at a time, mixing on low just until combined (don’t overmix).
Mix in sour cream, heavy cream, and vanilla on low until smooth.
Wrap pan in 2 layers foil. Place in roasting pan. Add hot water halfway up sides.
Pour filling over crust. Bake at 325°F for 60–70 min until edges set and center slightly jiggles.
Turn off oven, crack door, rest 1 hour. Cool to room temp, then chill overnight.
Whip cream + powdered sugar + vanilla to stiff peaks.
Pipe rosettes, add whole Biscoff cookies, and sprinkle crumbs. Slice and serve.