In a food processor, pulse blueberries several times until they start to puree. I like chunks of fruit in mine, so I don't make it too smooth. Transfer to a bowl and add all other jam ingredients and stir well.
Chill overnight or at least several hours.
For crust/base, process cashews in a food processor until fine and grain like. Add all other ingredients and process until a dough begins to form.
Reserve about 2 tablespoons of mixture.
Press dough into mini muffin cups lined with a small piece of parchment as shown in above photo. Press ½ inch into the center to make room for jam.
Scoop jam into each cup and top with fresh lemon zest and a sprinkle of reserved dough mixture.
Chill for about 15 minutes before serving.
Store in an airtight container in the refrigerator.