Making the Filling: Mix the chopped nuts and cinnamon together in a bowl and set aside until ready to use.
Making the Simple Syrup: In a small pot, combine the sugar & water; bring to a boil. Reduce heat to low, stirring now and then, until sugar is dissolved and mixture begins to thicken a bit, coating the back of a spoon. Stir in lemon juice. Remove pot from heat. Cool until ready to use.
Preheat oven to 350°F.
Remove phyllo cups from packaging and place them on a baking sheet.
Put about one heaping teaspoon of nut filling in each cup.
Bake for 10-15 minutes.
Remove from oven. While still hot, drizzle a little of the cooled simple syrup over each cup.
Serve warm or at room temperature. (Note: for a neater presentation, place each phyllo cup in a mini cupcake paper liner.)