Start by cooking the sweet potatoes. You can boil, microwave, or roast them—each method works depending on your time and flavor preference.

To boil, peel and cut the sweet potatoes into chunks, cover them with cold salted water, and bring to a boil. Cook for 15–20 minutes until fork-tender, then drain well and let them steam dry for a couple of minutes to avoid excess moisture.

If you’re short on time, pierce whole sweet potatoes with a fork and microwave on high for 5–8 minutes, flipping halfway through. Let them rest for a minute, then peel and mash. For the deepest flavor, roast them in the oven at 400°F for 45–60 minutes until soft, then scoop out the flesh.

Once the sweet potatoes are cooked, mash them until smooth. Add both sugars, salt, nutmeg, cinnamon, lemon zest, flour, vanilla extract, butter extract, melted butter, and beaten eggs. Mix everything together until the filling is creamy, silky, and well combined. Taste before adding the eggs and adjust the seasoning or sweetness as needed. Then spread the mixture evenly into a buttered baking dish.

To make the pecan topping, combine the crushed pecans, brown sugar, flour, melted butter, salt, and a touch of cinnamon in a bowl. Stir until the mixture becomes crumbly and well coated, then sprinkle it evenly over the sweet potato filling.

Bake the casserole at 350°F (175°C) for about 30–35 minutes, or until the top is golden brown and bubbling around the edges. Remove it from the oven and let it cool for about 10 minutes before serving, which helps the flavors settle and the topping firm up slightly.