Preheat the oven to 350 degrees F (175 degrees C). Grease and flour two 9x5-inch loaf pans (or 4 mini loaf pans).

Combine flour, pumpkin pie spice, baking powder, and salt in a mixing bowl.

Combine sugar, pumpkin purée, eggs, and oil in a small mixing bowl. Beat until just blended.

Stir the wet mixture into the dry with a wooden spoon until batter is just moistened. Fold cranberries and walnuts into the batter. Spoon the batter into the prepared loaf pans.

Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 50 to 60 minutes.