Preheat oven to 400°.
Place spinach in a microwave-safe bowl; cover and microwave at HIGH 2 to 3 minutes or until wilted; drain well. Combine spinach and vinegar; toss well.
Place flatbread rounds on an ungreased baking sheet. Rub cut sides of garlic over top of each flatbread round. Spread goat cheese evenly over rounds. Top with spinach and tomato. Sprinkle with basil, salt, and pepper.
Bake at 400° for 10 to 12 minutes or until pizza is lightly browned and thoroughly heated. Cut into quarters, and serve immediately.