Preheat oven to 375 degrees F. Line 12 muffin cups with paper liners or grease; set aside.
In large bowl, whisk together flour, sugar, baking powder, cinnamon, baking soda, salt, ginger, cloves and nutmeg; mix in ¼ cup of the walnuts.
In separate bowl, whisk together eggs, pumpkin puree, oil, buttermilk and vanilla; pour over dry ingredients. Stir just until dry ingredients are moistened.
Spoon into prepared muffin cups. Sprinkle with remaining walnuts. Bake in preheated oven for 20-25 minutes or until golden and tops are firm to the touch. Let cool in pan on rack for 5 minutes. Transfer to rack; let cool.