Preheat oven to 325 degrees. Grease two 8x4x3 inch loaf pans and set aside. In a medium bowl beat softened cream cheese; add 1/2 cup sugar, 1 tablespoon flour, 1 egg and the grated orange peel and continue beating until smooth. Set bowl aside.

In a separate bowl thoroughly combine the flour, baking soda, salt and spices. Set this bowl aside. In a large mixing bowl put pumpkin puree, vegetable oil, two eggs and 1 1/2 cups sugar and beat well.

Stir the flour and spice mixture into the pumpkin mixture until just combined. Fold in the chopped nuts, if using.

Divide 1/2 of the pumpkin batter into the bottom of the two prepared loaf pans spreading evenly. Spoon 1/2 of the cream cheese mixture into each pan and spread towards edges and corners. Divide half of remaining batter evenly into each pan and spread, covering the cream cheese mixture as best as you can.

Bake in a pre-heated 325 degree oven for 60-70 minutes or until a toothpick inserted into the center of each loaf comes out clean. Cool loaves in their pans for 10 minutes. Loosen edges with a knife then carefully remove to wire racks to cool completely. Wrap well and store in the refrigerator if not eaten immediately.