Chocolate Pudding Cake (Hot Fudge Sundae Cake)

2 cups all purpose flour
1½ cups granulated sugar
4 Tbsp. cocoa
4 tsp. baking powder
½ tsp. salt
1 cup milk
4 Tbsp. vegetable oil
2 tsp. vanilla
2 cups chopped nuts (optional)
1 cup packed brown sugar
¼ cup cocoa
3½ cups hottest tap water
Ice cream

Heat oven to 350°. Mix flour, granulated sugar, 2 tablespoons cocoa, the baking powder and salt in ungreased square, 9x13 inches. Mix in milk, oil and vanilla with fork until smooth. Stir in nuts. Spread in pan. Sprinkle with brown sugar and ¼ cup cocoa. Pour hot water over batter. Bake 40 minutes. While warm, spoon into dessert dishes and top with ice cream. Spoon sauce from pan onto each serving.
9 servings

Variations:
Butterscotch Sundae cake: Substitute 1 package (12 oz.) butterscotch chips (2 cups) for the nuts. Decrease brown sugar to ½ cup and the ¼ cup cocoa to 2 Tbsp.
Mallow Sundae Cake: Substitute 2 cups miniature marshmallows for the nuts.
Peanutty Sundae Cake: Substitute 1 cup peanut butter and 1 cup chopped peanuts for the nuts.
Raisin Sundae Cake: Substitute 1 cup raisins for the nuts.