For 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 1/3 cup of the olive oil, the lemon juice, 1/2 teaspoon salt, and 1/4 teaspoon pepper and process until smooth.

For the tomatoes, up to an hour before you're serving, combine the shallots, garlic, and vinegar in a medium bowl. Set aside for 5 minutes. Whisk in the remaining 1/3 cup olive oil, 1 teaspoon salt, and 1/2 teaspoon pepper. Add the tomatoes, stir gently, and set aside for 10 minutes. Stir in the basil and taste for seasonings.

To assemble the crostini, spread each slice of bread with a generous amount of whipped feta. With a slotted spoon, place the tomatoes on top. Put the crostini on plates and scatter with the pine nuts. Sprinkle with extra basil and serve.