Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking dish.

In a large pot, bring water to a boil and add the cubed butternut squash. Boil for about 15–20 minutes until tender.

Drain the boiled squash thoroughly and mash it in a mixing bowl until smooth.

Stir in granulated sugar, eggs, milk, melted butter, vanilla extract, cinnamon, nutmeg, and salt until fully combined.

Spread the mixture evenly in the prepared baking dish.

In a separate bowl, mix brown sugar and flour, then cut in cold butter to create coarse crumbs. Optionally fold in chopped pecans.

Sprinkle the topping evenly over the squash mixture in the baking dish.

Bake for 35–45 minutes until the center is set and topping is golden brown.

Let it cool slightly before serving warm.