Preheat oven to 400 degrees F (200 degrees C).

Grease a 9-inch square baking pan.

Mash cooked sweet potatoes until smooth.

In a medium bowl, combine mashed sweet potatoes, sugar (start with 1/2 cup and add more to taste), melted butter, whole milk, nutmeg, and cinnamon.

Mix well until all ingredients are fully incorporated.

Pour the sweet potato mixture into the prepared baking pan.

Bake for 20 minutes.

While the sweet potato mixture is baking, prepare the crunchy topping.

In a separate medium bowl, combine crushed corn flakes, chopped pecans, brown sugar, and melted butter.

Mix well to ensure all ingredients are evenly distributed.

After the sweet potato mixture has baked for 20 minutes, remove it from the oven.

Evenly spread the crunchy topping mixture over the top of the baked sweet potato mixture.

Return the dish to the oven and bake for an additional 10 minutes at 400 degrees F (200 degrees C), or until the topping is golden brown.

Remove from oven and let cool slightly before serving.