Preheat the oven to 350 degrees. Spray two standard muffin pans with non-stick cooking spray. Begin with the topping: Combine the flour, butter, demerara sugar, chopped pecans and cinnamon in a small bowl. Set aside. Move on to the muffins: In a medium bowl, whisk together the flour, salt, baking powder, baking soda, cloves, cinnamon and nutmeg. Set aside. In the bowl of an electric mixer, beat the butter and sugar at low speed until just blended. Add the eggs one at a time, beating well after each addition; continue beating at medium speed until very light and fluffy, a few minutes. Add the pumpkin and beat until combined, scraping down the sides of bowl as necessary. Turn the speed down to low and mix in the flour mixture until just combined. Use an ice cream scoop to transfer batter to muffin pans, filling each muffin tin about ¾ full. Sprinkle topping evenly over batter. Bake for about 30 minutes. Let the muffins cool on rack for about 10 minutes, then turn out onto rack to cool completely (use a butter knife to lift them out of pan). Notes: When making muffins, always fill any empty muffin tins halfway with water; this ensures that your muffins will bake evenly. If you want to make these muffins without the nut topping, increase the sugar in the muffins to 1¾ cup. Reheat muffins by giving them a quick blast in the microwave.