Preheat your oven to 350°F.
Spray a standard muffin pan with non-stick cooking spray.
Begin with the topping: Combine the flour, butter, brown sugar, chopped pecans (or walnuts) and cinnamon in a small bowl. The mixture will be quite wet. Set aside.
Now 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 softened butter and sugar at low speed until just blended.
Add the eggs one at a time, beating well after each addition; continue beating until very light and fluffy, a few minutes.
Add the cooked squash and beat until combined, scraping down the sides of bowl as necessary.
Add the flour mixture and mix on low speed until just combined.
Using a large spoon, transfer the batter to the prepared muffin pan, filling each cup completely full.
Using your fingers, divide the topping evenly over the batter.
Bake for 35 to 40 minutes, or until a cake tester or toothpick comes out clean.
Let the muffins cool in the pan for 10 minutes, then turn out onto rack to cool completely.
Note: This recipe makes 12 large muffins. For smaller muffins, divide the batter into 18 muffin cups and bake for 30 minutes