Good-Cooking - Warm Fudge-Filled Cheesecake

Ingredients

• 1/2 cup butter or margarine, softened
• 1/3 cup granulated sugar
• 1 cup all-purpose flour
• 1 tablespoon vanilla extract, divided
• 2/3 cup chopped pistachios
• 32 ounces cream cheese (at room temperature)
• 1 1/2 cups granulated sugar
• 4 large eggs
• 1 (12 ounce) package semisweet chocolate chips
• Sweetened whipped cream (optional)
• Chocolate shavings (for garnish)