Preheat oven to 375°F.
Slice squash into ¼-inch thick, 2-inch pieces. You will have about 1 ½ to 2 cups. Toss with 1 tablespoon olive oil, ½ teaspoon salt, and ¼ teaspoon black pepper.
Transfer to a baking sheet and bake for about 15 minutes or until squash is fork-tender. Set aside to cool.
Meanwhile, heat 1 tablespoon oil over medium heat in a large, ovenproof skillet. Add onions and a big pinch of salt and cook for about 15 minutes, or until golden.
Add garlic and cook for another minute or two. Transfer to a small bowl and allow to cool.
Whisk eggs with cream, salt and pepper to taste. Carefully stir in squash, onions, and sage. Heat 2 tablespoon over medium heat in skillet and swish it around so it gets the sides of the pan.
Pour in egg mixture, nudging vegetables so that they’re evenly spread, and turn heat down to low.
Cook gently, without stirring, for about 3 to 5 minutes or until edges and bottom are set. Gently stir in crumbled goat cheese and garnish with a few sage leaves.
Transfer skillet to oven and cook for about 5 to 10 minutes, until top is just set. Allow to cool slightly, or completely, before serving.