Preheat oven to 375°F. Coarsely grind nuts with brown sugar in processor. Blend in melted butter. Press mixture over bottom (not sides) of 9-inch-diameter springform pan with 2 1/2-inch-high sides. Bake until crust is set, about 12 minutes. Cool crust completely. Pour 3 cups cream into medium bowl. Pour 1/4 cup water into small heatproof bowl; sprinkle gelatin over. Let stand 15 minutes. Place bowl with gelatin in small skillet of barely simmering water; stir until gelatin dissolves, about 2 minutes. Remove bowl from water. Pour remaining 1/2 cup cream into gelatin. Pour gelatin mixture into cream in bowl; whisk gently until well blended. Using electric mixer, beat mascarpone and powdered sugar in large bowl until smooth. Beat in cream-gelatin mixture just until smooth. Pour filling over cooled crust. Cover and chill overnight. (Can be prepared 2 days ahead. Keep chilled.) Using small sharp knife, cut around pan sides to loosen cheesecake. Remove pan sides. Place cake on platter. Cut cake into wedges and serve with compote. *Italian cream cheese available at Italian markets and many supermarkets.