Line a standard muffin tin with 9 parchment cups, and set aside.
In a large food processor, combine the walnuts, maple syrup, coconut oil, and salt together. Pulse briefly, until the dough sticks together when pinched between your fingers. Scoop the dough by heaping tablespoons into the 9 parchment cups and use your fingers to press down and form a crust for each cup. Place the pan in the fridge to set while you prepare the filling.
To prepare the filling, simply combine all of the ingredients in a blender, starting with just 2 tablespoons of almond milk, and blend until completely smooth. Add more almond milk, 1 tablespoon at a time, as needed, to make the filling blend smoothly. (If your dates aren't soft enough to blend easily, soak them in warm water for 10 minutes beforehand.)
Remove the pan of crusts from the fridge, and spoon the batter evenly into the 9 cups. Smooth the tops, then place in the freezer to set completely, about 2 hours.
When the center of the filling is firm to the touch, the tarts are ready to serve! Remove the paper cups while the pumpkin tarts are still frozen. They will get softer as they come to room temperature, so be sure to serve them within 15-20 minutes of pulling them out of the freezer. Leftovers can be stored in an airtight container in the freezer for up to 3 months.
Nutrition information is for 1 of 9 servings. This information is automatically calculated, and is just an estimate, not a guarantee.Note: This recipe used to call for 1/4 cup shredded coconut in the crust, plus 1 more tablespoon of maple syrup. I found this made the crust ratio too large compared to the pumpkin filling, so I've started to omit it. If you've been making these tarts for years, I wanted to let you know about this change, in case you want to keep making the crust the same.If you don't have pumpkin pie spice at home, you can make your own blend, or swap this with 1 1/2 teaspoons ground cinnamon, 1/4 teaspoon ground ginger, and 1/8 teaspoon ground cloves.