Marble Cheesecake with Chocolate Crumb Crust

Crust Ingredients:
1 3/4 cups chocolate wafer crumbs
6 tablespoons unsalted butter, melted

Filling Ingredients:
3 (8-oz.) pkg. cream cheese, softened
1 cup sugar
1/8 teaspoon salt
3 eggs
1 cup sour cream
2 teaspoons vanilla
7 oz. bittersweet or semisweet chocolate, melted, cooled

Steps:
1) Heat oven to 350f.
2) In medium bowl, combine crust ingredients, mix well.
3) Press mixture evenly in bottom and halfway up sides of 9-inch springform pan & set aside.
4) In a large bowl, beat cream cheese on medium speed until smooth and creamy.
5) Add sugar and salt. Beat until smooth.
6) Scrape down bowl and beaters several times.
7) Add eggs, sour cream, and vanilla & beat just until blended and smooth.
8) Pour half of batter into medium bowl, stir in melted chocolate.
9) Alternately pour into pan 1 cup chocolate batter, then 1 cup vanilla until batter is used up.
10) To create marble design, pull blade of table knife through the batter making S shapes. Make sure you do not touch bottom or sides of pan.
11) Set pan on sturdy baking sheet.
12) Add 1-2 inches of water to a 13x9-inch pan & place in oven on bottom rack to add moisture during baking.
13) Place baking sheet and cheesecake in oven on center rack.
14) Bake 50-55 minutes or until top looks dull and is dry to the touch. Center should move slightly when side of pan is tapped, but shouldn't ripple as if liquid.
15) Turn off oven & remove pan of hot water, but leave cheesecake inside with the oven door opened for 10 minutes.
16) Cool cheesecake on wire rack, away from drafts, 2-3 hours or until completely cooled.
17) Refrigerate at least 4 hours.