Prepare 12 muffin tins by giving each cup a light spray of vegetable spray and add pre-cut strips of waxed papers that extend beyond the sides of the cups (to help with removing the treats when you're done.
Place all walnuts, cocoa powder, pitted dates, and oatmeal in a food processor and pulse for several seconds, until the ingredients are well-combined.
Add the flax and vanilla and pulse again for several seconds. Test the batter by pressing a bit of it between your fingers. It should be slightly sticky and hold together well. If necessary, pulse again for a few more seconds.
Press the batter into the bottom of your prepared muffin tins.
For the Creamy Peanut Butter Filling:
Using the same food processor bowl, add the peanut butter, 10 dates, 1 tablespoon of flax meal and 1 tablespoon of agave. Pulse until smooth.
Take a taste and determine if you'd like to add more flax or agave. If so, add one tablespoon of each.
When you've reached the desired taste and consistency, press the peanut butter filling over the chocolate based in your prepared muffin tins.
For the Chocolate Topping:
Place the chocolate chips in a microwave-safe bowl. Add 1 tablespoon of plant-based milk and 1 tablespoon of coconut oil. Stir these together and place in the microwave and cook for about 1 minute. Remove and stir. The chocolate should be mostly melted. If necessary, heat for another 30 seconds.
If the mixture is a bit too thick, then stir in another tablespoon of plant-based milk.
Drizzle the chocolate topping over the peanut butter cups.
Place the finished cups on a counter. Allow them to set for 10-15 minutes, up to an hour or so to let the chocolate set. They're delicious when the chocolate is still soft on the top, but a little less messy if you wait until it sets.
Remove the finished cups from the muffin tins by pulling up on the waxed paper pieces. Place them in a sealed container and keep refrigerated.