Pour the cold heavy cream into a large mixing bowl and beat it with a stand mixer or hand mixer until stiff peaks form. This usually takes around five to seven minutes, and you'll know it's ready when the cream holds its shape firmly on the beaters.
In a separate bowl, whisk together the sweetened condensed milk, pumpkin puree, vanilla extract, pumpkin pie spice, and salt. Stir until the mixture is completely smooth with no streaks of condensed milk left behind.
Add about half of the whipped cream into the pumpkin mixture and fold it in gently with a spatula. Once combined, add the remaining whipped cream and continue folding until the mixture is light, airy, and evenly colored.
Pour the finished mixture into your loaf pan and smooth the top with your spatula. Cover the pan tightly with plastic wrap so no ice crystals form on the surface while it freezes.
Place the pan in the freezer for at least six hours, though overnight gives you the best texture. Once it's firm enough to scoop, you're ready to serve.