Stir together first 4 ingredients; press crumb mixture evenly into bottom and 1 inch up sides of a 9-inch springform pan. Set aside.
Beat cream cheese, 1 cup sugar, and salt at medium speed with an electric mixer until smooth. Add eggs, 1 at a time, beating just until blended after each addition. Add sour cream and vanilla, beating just until smooth.
Divide batter in half; fold white chocolate and almond extract into 1 portion. Pour into prepared crust. Fold semisweet chocolate into remaining half of batter. Drop chocolate batter evenly over white chocolate layer; gently swirl with a knife to create a marbled effect.
Bake at 325° for 1 hour and 10 minutes or until almost set. Remove pan from oven, and run a knife around edge of pan to loosen sides. Cool on a wire rack.
Combine brown sugar, pecans, and butter in a small bowl. Sprinkle over cooled cheesecake. Cover and chill at least 8 hours. Store in refrigerator.
Tip: A little swirling goes a long way. If you're looking for the perfect marbled effect, don't overwork your batter. Too much swirling will cause a muddy look rather than the distinct color contrast you're looking for.