Prepare pan: Wrap 9-inch springform pan tightly with two layers of heavy-duty foil. Spray inside with non-stick spray. Preheat oven to 325°F. Place roasting pan in oven to heat.

Make crust: Pulse 24 Oreos in food processor until finely ground. Mix with melted butter and sugar until mixture resembles wet sand.

Bake crust: Press Oreo mixture firmly into bottom of pan. Bake 10 minutes. Cool while preparing filling.

Beat cream cheese: Beat softened cream cheese on medium speed 2-3 minutes until completely smooth. Scrape bowl frequently.

Add sugar: Add sugar and flour. Beat on medium-low 2 minutes. Add sour cream and vanilla, beating until smooth.

Add eggs: Add eggs one at a time on low speed, beating just until incorporated after each. Scrape bowl between additions. Don't overmix.

Fold in Oreos: Gently fold chopped Oreo cookies into batter with rubber spatula until evenly distributed.

Pour and prep: Pour filling over cooled crust. Tap pan on counter to release air bubbles.

Water bath: Place foil-wrapped pan in roasting pan. Pour hot water into roasting pan until halfway up sides of springform pan.

Bake: Bake 70-80 minutes until edges are set but center still jiggles like jello.

Cool gradually: Turn off oven and crack door open 4 inches. Cool in oven 1 hour. Remove from water bath and foil. Run knife around edge. Cool to room temperature (2-3 hours), then refrigerate 6+ hours or overnight.

Make whipped cream: Beat cold heavy cream, powdered sugar, and vanilla until stiff peaks form, 3-4 minutes.

Decorate: Remove springform ring. Spread whipped cream over top. Arrange whole Oreos on top. Drizzle with chocolate sauce if desired.

Serve: Slice with hot, clean knife, wiping between cuts.