PreparationFor Sauce: Melt butter in heavy medium saucepan over medium heat. Add sugar, cream and salt and whisk until sauce is smooth and comes to simmer. Remove from heat; mix in vanilla. Cool sauce completely, stirring occasionally. For Crust: Preheat oven to 350°F. Butter bottom of 9-inch-diameter springform pan. Using electric mixer, beat brown sugar, butter and vanilla extract in medium bowl until smooth. Add flour and 2/3 cup chopped pecans and stir until moist clumps form. Press dough onto bottom and 1/2 inch up sides of prepared pan. Bake until crust is set and beginning to brown, about 12 minutes. Cool crust completely. Spoon ice cream into crust, pressing to compact. pour 1/2 cup sauce over. Using tip of small knife, swirl sauce and top layer of ice cream, creating marbled pattern. Cover pie and freeze 12 hours. (Sauce and pie can be prepared 3 days ahead. Cover remaining sauce and refrigerate. Keep pie frozen.) Run small sharp knife around pan sides to loosen pie. release pan sides. Arrange toasted pecan halves decoratively around top edge of pie, if desired. Let pie stand 5 minutes to soften slightly. Rewarm remaining sauce. Cut pie into wedges and serve with sauce.
PreparationFor Sauce: Melt butter in heavy medium saucepan over medium heat. Add sugar, cream and salt and whisk until sauce is smooth and comes to simmer. Remove from heat; mix in vanilla. Cool sauce completely, stirring occasionally. For Crust: Preheat oven to 350°F. Butter bottom of 9-inch-diameter springform pan. Using electric mixer, beat brown sugar, butter and vanilla extract in medium bowl until smooth. Add flour and 2/3 cup chopped pecans and stir until moist clumps form. Press dough onto bottom and 1/2 inch up sides of prepared pan. Bake until crust is set and beginning to brown, about 12 minutes. Cool crust completely. Spoon ice cream into crust, pressing to compact. pour 1/2 cup sauce over. Using tip of small knife, swirl sauce and top layer of ice cream, creating marbled pattern. Cover pie and freeze 12 hours. (Sauce and pie can be prepared 3 days ahead. Cover remaining sauce and refrigerate. Keep pie frozen.) Run small sharp knife around pan sides to loosen pie. release pan sides. Arrange toasted pecan halves decoratively around top edge of pie, if desired. Let pie stand 5 minutes to soften slightly. Rewarm remaining sauce. Cut pie into wedges and serve with sauce.