Pre-heat the oven to 375 degrees.
Place the cubed squash on a large baking sheet. Drizzle with 1 tablespoon of olive oil, season with kosher salt and fresh ground pepper, and toss to coat. Arrange the squash in an even layer. (Ideally, you want a little bit of space between the cubes.) Roast for 30 minutes until tender and lightly browned, stirring once halfway through the cooking time.
Meanwhile, caramelize your onions. Heat 1½ tablespoons of olive oil in a large nonstick skillet over medium heat. When the oil is hot and shimmering, add the onions and a pinch of kosher salt and cook, stirring occasionally until very soft, about 15-20 minutes. (Be careful not to burn the onions! If they start to brown, reduce the heat to medium-low.) Stir in the balsamic and cook for 1 minute more, then remove the onions from the heat and briefly set aside.
Moving on to the tostada shells! Arrange the tortillas on a large baking sheet. Lightly brush both sides of the tortillas with the remaining 2 teaspoons of olive oil and season with kosher salt and fresh ground pepper. Bake for 6-8 minutes per side or until lightly browned and crisp. (Keep an eye on them, friends. They can go from browned to burnt very quickly.) If you’re capable of multitasking, I recommend baking the tostada shells during the last 15 minutes of the squash roasting time.
Assembly time! Spread each tostada with about 2 tablespoons of hummus. Top with caramelized onions and roasted squash. Finish with a little crumbled goat cheese, a sprinkling of fresh thyme, and few pomegranate arils (if using), and serve!