Filling:
Preheat oven to 350 degrees F. Unwrap caramels and combine
in a saucepan with sweetened condensed milk and butter.
Cook
and stir over medium heat until melted and smooth. Remove
from heat and set aside.
Cake:
Melt butter and chocolate together, either on the stove
or in the microwave.
Add
the water, sugar, eggs, flour, salt, baking soda and
vanilla. Beat until smooth and creamy.
Spread
half of the cake batter into a greased 9 by 13 inch
pan. Bake for 15 minutes, until the centre is set. Remove
from oven.
Spread
filling evenly over the cake. Spread the remaining cake
batter over the filling. Sprinkle the nuts over the
top.
Return
to the oven and bake 40 minutes, until cake springs
back when touched. Cool completely before cutting.