Preheat the oven to 400 F (200 C) and melt the butter.
Measure out the flour, sugar, baking soda, salt, and spices in a medium bowl and whisk together.
In another bowl, whisk together the egg, pumpkin puree, and condensed milk.
Pour the wet ingredients into the dry ingredients and stir everything together until well incorporated.
Add the melted butter and stir it in.
Grease your muffin tins with some butter. Pour about ¼ cup of batter into each form. Evenly distribute the batter into 12 muffin forms.
Bake for 25 minutes.
Cream cheese frosting (optional)
Whisk the room temperature butter in a bowl, add the soft cream cheese and the vanilla extract. Sift in powdered sugar. Use a hand mixer to mix it for 2-3 minutes until you get a light texture. Let it chill in the fridge for 30 minutes. Put it in a piping bag and decorate your muffins. Sprinkle on some chopped nuts for extra decoration.