Start by preheating your oven to 400°F so it's fully hot by the time your squash goes in. While it heats, dice the butternut squash into small, even cubes so they roast at the same pace. I also like to slice my baguette now so everything is ready to go without scrambling later.
Toss the diced squash and chopped cranberries with 1 tablespoon of olive oil, the maple syrup, salt, and pepper. Spread them in a single layer on a baking sheet and roast for about 15 minutes, stirring once halfway through. You want the edges lightly caramelized, not mushy.
While the squash roasts, brush your baguette rounds with the remaining olive oil on both sides. Place them on a separate baking sheet and toast in the same oven for 5 to 7 minutes until golden and crisp. Keep an eye on them since they can brown quickly near the end.
As soon as the toasts come out of the oven, rub the cut side of the garlic clove gently over the warm surface of each slice. The heat releases just enough flavor without making it taste raw or sharp, which is the trick I learned after a few too-garlicky batches.
Top each toasted slice with a few torn pieces of fresh mozzarella while the bread is still warm so it softens slightly. Spoon the roasted squash and cranberry mixture generously over the cheese, making sure every bite gets a bit of both.
Sprinkle the chopped fresh sage over the top, then finish with a light drizzle of balsamic glaze. Serve immediately while the bread is still crisp and the cheese is just starting to melt into the warm topping.