Preheat your oven to 375°F (190°C) and lightly grease your baking dish or ovenproof skillet.
Chop the fresh sage leaves finely and set aside.
In a mixing bowl, whisk together the eggs until smooth, then stir in the shredded cheddar, chopped sage, and a pinch of salt and pepper.
Pour the olive oil into the prepared baking dish and spread the roasted pumpkin cubes evenly across the bottom.
Pour the egg mixture over the pumpkin, making sure it's evenly distributed.
Place the dish in the oven and bake for about 20 minutes, until the eggs are puffed and set, with a lightly golden top.
Remove the frittata from the oven and let it cool slightly before slicing.
Slice into wedges and serve warm, enjoying the vibrant flavors and fluffy texture of this seasonal dish.