Preheat the oven to 400°F. Cut the ends from the squash and, using a long spoon, scoop out the seeds and discard. Cut the squash into ¼-inch-thick rounds. Arrange squash rounds on a baking sheet. Drizzle with olive oil and season lightly with salt and pepper. Roast until just tender, about 15 minutes. Remove from the oven.
While squash roasts, combine cream, garlic and thyme in a small saucepan and bring to a simmer. Remove from the heat and set aside to infuse for 15–20 minutes. Discard garlic and thyme, then stir in ¾ cup shredded gouda.
Melt 2 tablespoons butter. Place the bread crumbs and remaining ¼ cup shredded gouda in a small bowl. Add the melted butter and stir to combine. Set aside.
Butter a shallow gratin or casserole dish with the remaining 1 tablespoon butter. Arrange the squash in the dish, layering as needed. Pour the cream mixture over top and tilt dish so cream settles evenly around the squash. Scatter the bread crumb mixture over top.
Bake until mixture is bubbling and top is golden brown and crisp, about 20 minutes. (Run under the broiler if you want more color and crispness on top.) Serve warm.