Line the base of an 8 × 8-inch baking pan with parchment paper. Allow enough parchment to extend over the sides so the chilled fudge can be lifted from the pan easily.
Place the packed dates, almond butter, pumpkin purée, pumpkin pie spice, and salt in a medium saucepan. Set the pan over medium-low heat.
Cook for approximately 10 minutes, stirring frequently to prevent scorching or sticking. Continue until the almond butter has melted, the dates are thoroughly warmed, and the mixture has developed a very thick consistency.
Transfer the cooked mixture to a food processor. Blend until creamy and uniform, pausing periodically to scrape down the sides of the bowl. Continue processing until the texture is as smooth and silky as possible.
Spoon the blended pumpkin mixture into the parchment-lined baking pan. Use a spatula to distribute it evenly, pressing the mixture into the corners and smoothing the surface.
Scatter the raw pumpkin seeds evenly across the top of the fudge and press them lightly into the surface.
Place the pan in the freezer for a minimum of 3 hours, or until the fudge is sufficiently firm to cut cleanly.
Lift the set fudge from the pan using the parchment-paper overhang. Cut it into bars of the preferred size, finish with flaked sea salt as desired, and serve immediately.