Chocolate-Chip Ice-Cream-Sandwich Cake with Butterscotch Sauce

INGREDIENTS

Egg, large

1/2 cup

Corn syrup, dark

1 1/2 cups

All purpose flour

3/4 tsp

Baking soda

3/4 cup

Brown sugar, packed dark

1 1/2 cups

Chocolate chips, semisweet

1/2 cup

Golden brown sugar, packed

1/2 tsp

Salt

1/2 cup

Sugar

2 tsp

Vanilla

6 tbsp

Butter, unsalted

1/2 cup

Whipping cream

3 pints

Chocolate or vanilla ice cream

9 tablespoons (1 stick plus 1 tablespoon) unsalted butter, room temperature