1. Preheat oven to 300° with 2 racks set on lowest rungs. Combine crumbs, butter, and 1/2 cup sugar in a bowl. Press over bottom and up sides of a 10-in. springform pan; set aside.
2. Blend cream cheese and remaining 1 3/4 cups sugar in the bowl of a stand mixer on low speed (do not whip or add air). Add eggs, 1 at a time, scraping bowl between additions. Pour in cream, chocolate, and extract and mix just to blend. Mix in flour. Pour into prepared pan.
3. Put a rimmed baking sheet on bottom rack and fill halfway with water. Set cake on rack above it. Bake until top is set but center still jiggles slightly when shaken, 1 1/4 to 1 1/2 hours. Let cool on a rack 1 hour. Chill 3 hours and up to 3 days before serving. To serve, sprinkle with candies and cut with a hot, wet knife.