In a medium bowl, combine your finely ground gingersnap crumbs, 3 tablespoons of sugar, and melted butter until the mixture resembles wet sand.

Press the crumbs firmly into the bottom and up the sides of a 9-inch glass pie plate. Bake for 8 to 10 minutes until set, then let cool completely.

In a heavy pot or Dutch oven, whisk together the egg yolks, milk, 1/2 cup of the sugar, salt, pumpkin pie spice, and pure pumpkin puree.

Sprinkle the unflavored gelatin over the top and let it bloom for a few minutes. Cook over low heat, stirring constantly until the gelatin dissolves and the custard thickens to coat a spoon. Remove from heat and cool to room temperature.

In a clean stand mixer bowl, beat the egg whites on medium speed until soft peaks form. Gradually add the remaining 1/4 cup of sugar and whip until stiff, glossy peaks form.

Gently fold one-third of the meringue into the cooled pumpkin mixture. Add the remaining meringue and orange zest, folding carefully until no white streaks remain without deflating the mixture.

Pour the fluffy pumpkin filling into the cooled, pre-baked crust, smooth the top, and refrigerate for at least 4 to 6 hours or overnight until fully set.

Whip the heavy cream with powdered sugar until pillowy peaks form, spread generously over the chilled pie, dust with cinnamon, and serve.