Preheat oven to 350F (175C). Spray a 10x10-inch baking pan with nonstick cooking spray, set aside.
In a medium bowl, mix the flour, salt, baking powder, soda, and spices.
In another larger bowl whisk the eggs with syrup and oil. Mix in pumpkin puree. Add dry ingredients in wet and mix until nicely combined.
Spread the batter into the prepared baking sheet. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean with no crumbs on it. Remove from the oven and allow to cool completely before frosting it.
For the frosting:
In a medium bowl, beat cream cheese with powdered sugar on low speed until smooth. Add vanilla and Greek yogurt. Mix on low speed until smooth and spreadable.
Once the pumpkin bars have cooled, spread frosting on top.
Sprinkle with walnuts and goji berries. Cut into bars and enjoy!
Store in the air-tight container covered in the refrigerator. As a measure, I used US cup (240ml). For thinner bars use15x10-inch jelly roll pan - yields more bars (around 30 bars). For ticker bars use the10x10-inch baking pan - yields less bars (16 bars).