Topping:
1/2 c. butter
1/4 c. sugar
1/4 c. plus 2 tbsp packed light brown sugar
2 tsp ground cinnamon
1/4 tsp ground nutmeg
Pinch of salt
1 c. flour
1/2 c. chopped English walnuts
Muffins:
1 1/2 c. firmly packed brown sugar
1/3 c. vegetable oil
1/3 c. unsweetened applesauce
1 large egg
1 1/2 tsp vanilla
2 1/2 c. flour
1/2 tsp baking soda
1 1/2 tsp baking powder
1/4 tsp salt
3/4 tsp ground nutmeg
2 tsp ground cinnamon
1/2 tsp ground cloves
1/4 tsp ground ginger
1 c. buttermilk
1 1/4 c. chopped English walnuts
2 1/2 c. apple, chopped into 3/4-inch pieces
All you do:
For topping: In a small saucepan, melt butter over medium heat. Remove pan from the heat and add the granulated sugar, brown sugar, cinnamon, nutmeg and salt. Stir with a rubber scraper, pressing when necessary, until smooth.
Add flour and mix until well-blended and pasty.
Fold in chopped walnuts; set aside.
For muffins: Preheat oven to 350 degrees.
In a large bowl, whisk together brown sugar, oil, applesauce, egg and vanilla until smooth.
In a separate bowl, sift together flour, soda, baking powder, salt, nutmeg, cinnamon, cloves and ginger. Stir oil mixture into flour mixture alternately with buttermilk. Stir in walnuts. Fold in apples, mixing until just combined.
Spoon into greased muffin cups, filling to almost full. Break up the topping mixture with your fingers into medium–sized pieces. Sprinkle the topping pieces over the muffin batter evenly.
Bake 25 to 30 minutes or until golden brown and tops spring back.