Step 1: Preheat your oven to 350°F (175°C). In a bowl, combine the chocolate cookie crumbs and melted butter. Press the mixture firmly into the bottom and sides of a 9-inch tart pan.
Step 2: Bake the crust for 8-10 minutes. Remove from the oven and let it cool completely on a wire rack while you prepare the filling for the pumpkin spice chocolate tart recipe.
Step 3: In a small saucepan over medium heat, whisk together the heavy cream, pumpkin purée, cinnamon, ginger, nutmeg, and salt. Bring to a gentle simmer, but do not let it boil.
Step 4: Place the chopped dark chocolate in a heat-proof bowl. Pour the hot pumpkin cream mixture over the chocolate and let it sit for 2 minutes without stirring.
Step 5: Add the vanilla extract and gently whisk the mixture starting from the center and moving outwards until a smooth, glossy ganache forms.
Step 6: Pour the filling into the cooled tart crust. Smooth the top with a spatula and refrigerate for at least 4 hours, or until the pumpkin spice chocolate tart recipe is completely set.
Step 7: Before serving, garnish with whipped cream or a dusting of cocoa powder if desired.