Preheat the oven to 375 degrees F.
Drizzle the baguette slices with olive oil and arrange on a sheet pan. Toast in the oven, about 7-8 minutes per side. Once the bread is toasted, rub it with a whole garlic clove.
In a large skillet, heat 1 tablespoon olive oil over medium heat. Sauté the onions until they start to turn soft and translucent, about 3-4 minutes. Stir in the minced garlic, oregano, thyme, salt, pepper and red pepper flakes and continue sautéing until fragrant, about 1 minute.
Pour in the balsamic vinegar and diced tomatoes. Simmer until thickened, about 5 minutes.
Arrange the goat cheese and tomatoes in a baking dish. Spoon the tomatoes in between the cheese with some tomatoes on top. The cheese should still be showing through the tomatoes.
Bake for 20-25 minutes until the cheese is golden and bubbling at the edges.
Turn the broiler on high and broil for 1-2 minutes until the cheese has browned slight at the edges. (The dish should be on the top rack about 4-5 inches from the broiler.)
Sprinkle with chopped parsley before serving with toasted garlic bread.