Maybe it was a butter pecan pudding mix, rather than butterscotch. Just a thought. I make a butter pecan pie, but it uses vanilla pudding with butter flavoring:

Butter Pecan Toffee Pie

1 graham cracker or shortbread crust
1 package (small) instant vanilla pudding
1 1/2 c. milk
1 tsp. butter flavoring
1 tsp. caramel flavoring
8 oz. cool whip
1/2 finely chopped pecans
1/2 c. toffee bits

Combine pudding, milk and flavorings and mix until well blended. Fold in thawed whipped topping. Lightly stir in nuts and toffee bits, reserving a few for the top. Pour into graham cracker crust, and sprinkle with reserved nuts and toffee bits. Chill.