Pineapple Upside Down Cake

1 yellow cake mix (Use directions on back of cake)


Sauce
1/3 cup brown sugar (packed)
1 tbsp cornstarch
Stir in 1 cup pineapple juice from drained fruit or buy a can at grocery store (add water if necessary to make 1 cup)

Melt butter in pans
Add walnuts to cover pan
Add pineapple rings then add cake mixture
Bake at cake mixture temperature on box


Before serving cake add sauce slightly warm.