In a small bowl, combine the cracker crumbs, brown sugar, butter and vanilla. Press onto the bottom and 2 in. up the sides of a greased 9-in. springform pan. Bake at 350° for 6-8 minutes or until set; cool on a wire rack. Sprinkle with toffee bits., In a small bowl, beat cream cheese and sugar until smooth. Beat in sour cream and vanilla. Add eggs; beat on low speed just until combined. Pour into crust. Place pan on a baking sheet. , Bake at 350° for 50-60 minutes or until center is almost set. Cool on a wire rack for 10 minutes. Carefully run a knife around the edge of pan to loosen., For topping, combine the sour cream, sugar and vanilla; spread over cheesecake. Bake 5 minutes longer. Cool on a wire rack for 1 hour. Refrigerate overnight. Remove sides of pan. Sprinkle with toffee bits.