Preheat oven to 400°F and position the oven rack in the middle.
Place 1 cup whole cherry tomatoes in a 2-quart baking dish or cast iron skillet and drizzle with olive oil.
Top tomatoes with basil pesto, minced garlic, Kosher salt, and black pepper; toss to coat evenly.
Bake tomatoes for 15 minutes until soft and fragrant.
While tomatoes roast, in a large bowl, stir together sour cream and chopped basil.
Add mozzarella, provolone, and Parmesan cheeses to the sour cream mixture and combine well.
When tomatoes are done, add the cheese mixture to the baking dish and toss to combine.
Slice remaining 1 cup of cherry tomatoes in half and arrange on top of the cheese.
Return the dish to the oven and bake for an additional 20 minutes until cheese is melted, golden on top, and edges are bubbling.
Remove from oven and top with fresh basil before serving. Serve warm with crusty bread, crackers, or chips.