Chocolate Chip Ice Cream Sandwich Cake, Butterscotch Sauce

Directions

1. For Butterscotch Sauce: Combine first 5 ingredients in heavy medium saucepan. Stir over low heat till both sugars dissolve. Increase heat and boil till large bubbles break on surface and sauce drops thickly from spoon, stirring constantly, about 2 min. Remove from heat; whisk in cream and vanilla (mix may bubble vigorously). (Can be made 3 days ahead. Cover; chill. Rewarm slightly over low heat before using.)
2. For Cookies: Preheat oven to 350 degrees. Line two 9-inch-diameter cake pans with 1 1/2-inch-high sides with parchment paper; butter paper.
3. Sift flour, baking soda and salt into small bowl. Using electric mixer, beat butter and both sugars in large bowl till well blended. Add in egg and vanilla and beat till smooth. Beat in flour mix. Stir in chocolate chips. Drop half of dough by large spoonfuls into each prepared pan; spread proportionately. Bake cookies till light golden brown, about 18 min. Cold cookies in pans on racks. Carefully turn out cookies; peel off parchment.
4. Place 1 cookie, top-side up, in 9-inch springform pan with 2 3/4-inch-high sides. Drizzle 1/4 c. sauce over. Spread proportionately with ice cream; drizzle with 1/2 c. sauce. Top with remaining cookie, top-side up; press gently to adhere. Drizzle with 2 Tbsp. sauce. Cover pan and freeze ice cream cake at least 5 hrs. Cover and refrigerateremaining sauce. (Cake and sauce can be prepared 3 days ahead.)
5. Cut around cake with small knife to loosen. Release pan sides. Let cake stand till ice cream is slightly softened, about 20 min. Rewarm butterscotch sauce over low heat. Cut cake into wedges; serve with sauce.
6. This recipe yields 10 to 12 servings.
7. Comments: Here"s a party-size ice cream sandwich which everyone will love. We use two 9-inch-diameter cake pans so which the cookies keep their round shape when baking. And there"s no need for last-minute fuss; this can be made up to three days ahead.