STREUSEL TOPPING (below) :

3 med. Golden Delicious apples
2 tbsp. sugar
1 c. butter, softened
1 1/2 c. sugar
1 (16 oz.) container sour cream

2 1/2 c. flour
1 tbsp. baking powder
2 tsp. baking soda
2 tsp. vanilla extract
4 lg. eggs

ABOUT 2 HOURS BEFORE SERVING OR EARLY "IN DAY":

Prepare Streusel Topping; set aside.

STREUSEL TOPPING: In bowl, knead 1 cup chopped walnuts, 2/3 cup all-purpose flour, 1/4 cup packed brown sugar, 4 tablespoons butter, and 1 teaspoon cinnamon into large pieces. Peel, core, and thinly slice apples. In bowl, toss apples with 2 tablespoons sugar. Grease 14x10 inch roasting pan. Preheat oven to 350 degrees.

In large bowl, with mixer at medium speed, beat butter with 1 1/2 cups sugar until light and fluffy. Add sour cream and remaining ingredients; beat at low speed until blended, constantly scraping bowl.

At medium speed, beat 1 minute. Spread batter in pan; arrange apple slices on top (going out to edge of pan); otherwise, batter will bake up over apples. Sprinkle with streusel topping.

Bake 45 to 50 minutes until cake pulls away from pan walls. Cool in pan on wire rack 10 minutes. Or, cool to serve later. Yield: 18 servings. Each serving: about 395 calories, 23 g. fat; 58 mg. cholesterol, 340 mg. sodium.