Place 2 cups cold heavy cream, 1 (14-ounce) can sweetened condensed milk, 1 tablespoon pumpkin pie spice, and 1/2 teaspoon kosher salt in the bowl of a stand mixer (or large bowl if using an electric hand mixer). Attach the whisk attachment and turn on to low speed. Slowly increase the speed to high and whisk until soft peaks form, 2 to 3 minutes.