Lightly grease eighteen 2-1/2-inch or seventy-two 1-3/4-inch muffin pans* or line them with paper bake cups. Set aside.
In a large bowl, stir together flour, baking powder, pumpkin pie spice, and salt. Make a well in center.
In another bowl, mix eggs, sugar, pumpkin, cooking oil, and milk. Add to flour mixture. Stir until combined. Fold in walnuts and raisins.
Fill prepared pans about 2/3 full with batter. Bake in a 375 degree F oven for 20 to 25 minutes or until golden for 2-1/2 inch muffins or 12 to 15 minutes for 1-3/4-inch muffins. Remove from pans; serve warm. Makes 18 regular-size muffins or 72 mini-muffins.
For jumbo muffins, bake batter in eight 3-1/2-inch muffin pans in a 350 degree F oven for 25 to 30 minutes or until golden.