Preheat oven to 200°C (400°F).
Add chopped potatoes to a large casserole dish. Drizzle generously with olive oil and season with salt. Toss to coat evenly. Bake for 20–30 minutes, until nearly fork-tender and lightly browned.
In a bowl, combine mushrooms with balsamic vinegar and half of the minced garlic. Set aside to marinate.
Remove potatoes from oven. Add marinated mushrooms, red bell pepper, red onion, fennel seeds, smoked paprika, dried herbs, remaining garlic, salt, and pepper. Toss well, lightly smashing some potatoes for extra flavor absorption. Add a drizzle of olive oil if needed.
Return to oven for 20 minutes until vegetables soften and caramelize.
Stir in peas, cherry tomatoes, kale, and grated parmesan. Mix thoroughly.
Add small dollops of goat cheese across the dish. Gently push them slightly into the mixture without fully blending.
Sprinkle shredded mozzarella evenly over the top.
Bake for another 15 minutes, until golden and bubbling.
Let the Cheesy Veggie Potato Bake rest for 10 minutes before serving.