Preheat oven to 350 degree F. Grease a 15x10x1-inch baking pan; set aside.

In a large mixing bowl stir together the flour, baking powder, orange peel, baking soda, and salt. Set the flour mixture aside.

In a medium bowl combine eggs and brown sugar. Stir in pumpkin, oil, milk, and vanilla. Then stir in carrots and chopped walnuts.

Add egg mixture to flour mixture, stirring with a wooden spoon until combined. Spread batter into the prepared pan. Bake for 20 to 25 minutes or until a wooden toothpick inserted near the center comes out clean. Cool in pan on a wire rack. Spread with Orange Icing; cut into triangles or bars. If desired, garnish each with a walnut half. Store in an airtight container in the refrigerator for up to 3 days. Makes 36 bars.

In a mixing bowl combine powdered sugar and enough of the orange liqueur or orange juice to make an icing that is easy to drizzle.

Bake bars as directed; cool completely. Do not drizzle with icing. Place cut bars in a freezer container and freeze for up to 1 month. Before serving, thaw for 15 minutes. Prepare Orange Icing and drizzle as directed.