Pumpkin and Pecan Semifreddo with Caramel Sauce

For semifreddo:

Line 9 1/4x5 1/4x3-inch metal loaf pan with plastic wrap. Blend gingersnap crumbs and brown sugar in processor until combined. With machine running, slowly add butter; process until moist crumbs form. Press crumb mixture onto bottom and 2 inches up sides of prepared loaf pan. Chill 10 minutes.

Whisk pumpkin, honey, and spices in large bowl to blend. Set aside.

Stir 1 cup sugar, 1/4 cup water, and corn syrup in heavy medium saucepan over low heat until sugar dissolves. Increase heat and boil syrup without stirring until candy thermometer registers 248°F, about 10 minutes.

Meanwhile, using electric mixer, beat egg whites in medium bowl to soft peaks. Gradually beat in hot sugar syrup; beat until mixture is cool, about 7 minutes.

Fold 1/3 of egg white mixture into pumpkin-spice mixture to lighten. Fold in remaining egg white mixture. Fold in pecans and toffee bits. Spoon mixture into prepared crust. Cover with plastic wrap and freeze until frozen, about 8 hours. (Can be made 3 days ahead. Keep frozen.)

For caramel sauce:

Stir sugar, 1/4 cup water, and corn syrup in heavy medium saucepan over low heat until sugar dissolves. Increase heat and boil without stirring until syrup is deep amber color, occasionally brushing down sides of pan with wet pastry brush and swirling pan, about 8 minutes. Remove from heat. Whisk in 1/2 cup cream, butter, and then crème fraîche (mixture will bubble). Stir in vanilla and salt. (Can be made 1 day ahead. Cover and refrigerate. Stir over medium heat to rewarm before serving.)

Wipe sides of loaf pan with hot wet cloth. Invert semifreddo onto platter; remove plastic. Cut into 1-inch-thick slices and serve with warm caramel sauce and whipped cream.