Step 1: Preheat your oven to 325°F (165°C). Grease and flour two 9x5-inch loaf pans; set aside.
Step 2: In a large mixing bowl, using an electric mixer, cream together the softened butter and granulated sugar until light and fluffy, about 2-3 minutes.
Step 3: Add the eggs one at a time, beating well after each addition until fully incorporated.
Step 4: Stir in the pumpkin puree and sour cream until the mixture is smooth and well combined.
Step 5: In a separate medium bowl, whisk together the all-purpose flour, baking powder, baking soda, salt, ground cinnamon, ground cloves, and ground nutmeg.
Step 6: Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix the batter.
Step 7: Divide the batter evenly between the two prepared loaf pans, smoothing the tops with a spatula.
Step 8: Bake for 65-75 minutes, or until a wooden skewer or toothpick inserted into the center of the bread comes out clean.
Step 9: Let the bread cool in the pans on a wire rack for 10-15 minutes. Then, carefully remove the loaves from the pans and transfer them directly to the wire rack to cool completely before slicing and serving.