Preheat the oven to 350 degrees F, and mist a 5-cup loaf pan with non-stick spray.
Place the flour, brown sugar, cinnamon, baking soda, salt, nutmeg, and cloves in a large mixing bowl and whisk to combine.
Place the pumpkin, butter, eggs, Greek yogurt, milk, and vanilla in a smaller bowl and whisk to combine.
Add the pumpkin mixture to the flour mixture, and fold together until just barely combined.
Transfer the batter to the prepared pan, and bake for 60 to 75 minutes, or until a toothpick inserted in the thickest part of the bread comes out clean or with a few moist crumbs.
Cool for 20 minutes in the pan, then remove to a wire rack and allow to cool completely before slicing.
*Sour cream or buttermilk can be substituted. If you don’t have buttermilk, you can substitute by stirring 3/4 teaspoon of lemon juice or white vinegar into 3 tablespoons of regular milk. Allow the mixture to stand for 5 minutes, or until thickened and slightly curdled.