Line an 8x8-inch metal baking pan with parchment paper. Spray paper with nonstick cooking spray.
In a medium pot, combine sugars, maple syrup, butter, pumpkin, cream, pumpkin pie spice and salt over medium heat. Stir until butter is melted and all ingredients are combined. Bring to a simmer and cook 10 to 12 minutes or until temperature reaches 238 degrees on a candy thermometer. Stir in walnuts.
Pour mixture into lined baking pan. Cool 1 hour on the counter, then refrigerate an additional 1 hour. Slice into 36 squares.