Preheat your oven to 180°C (350°F).

In a large pot of boiling salted water, cook the short pasta for about 8-10 minutes until al dente. Drain and set aside.

Heat a tablespoon of olive oil in a large skillet over medium heat. Add the sliced onions and cook for about 15-20 minutes until caramelized.

Add balsamic vinegar to the pan and cook for another 5 minutes until the onions are sticky.

In a mixing bowl, combine double cream with crumbled goat cheese. Season with salt and black pepper, and mix well.

In a baking dish, combine pasta, caramelized onions, and cheese mixture. Stir gently until well mixed.

Sprinkle grated mozzarella and grated Parmesan cheese over the top of the pasta mixture.

Bake for 20-25 minutes until the cheese is bubbly and golden.

Let the dish rest for a few minutes, then garnish with fresh thyme if desired before serving.