Preheat oven to 425°F. Wrap beets individually in foil and place in oven. Roast for 45 minutes or until tender.
Once cooled, remove the peel with your hands. With a knife, dice the beets into small cubes.
Reset oven to 400°F. Slice the puff pastry into 9 squares, and press them into muffin tins.
Pierce the bottoms repeatedly with a fork and bake for 15 to 20 minutes until golden. If the center of the puff pastries come out raised, simply press them down with your fingers.
In a bowl, combine ricotta, honey, and a pinch of salt. Transfer the ricotta to a Ziploc® bag. With scissors, cut off one corner of the bag and pipe the ricotta into the center of the puff pastry tarts.
Top each tart with cubed roasted beets, a pinch of black pepper, and a pinch of thyme. Drizzle tarts with additional honey. Serve at room temperature.