First, make the whipped feta. Place the feta and cream cheese in the bowl of a food processor fitted with the steel blade. Pulse until the cheeses are mixed. Add the lemon juice, 1/2 teaspoon salt, and 1/4 teaspoon pepper and turn on the food processor. With the food processor running, slowly add the olive oil in a steady stream through the tube. Turn off the food processor.
Place a dollop of whipped feta in the center of each cucumber slice. Top with sun-dried tomatoes and fresh basil. Serve.