• Heat the oven to 350 °F, then lightly grease a large oven-safe casserole dish, about 9x13 inches. The prepared dish should have a thin, even coating so the set filling releases easily when served.
• Process the pumpkin and thawed cauliflower until completely smooth in a food processor. Stop and check for a uniform orange puree with no grainy cauliflower pieces around the bowl.
• Add the vegan butter or ghee, almond milk, sweetener, eggs, coconut flour, vanilla, and salt, then process again until blended. The finished mixture should look glossy and thick enough to mound softly on a spoon.
• Spoon the filling into the prepared casserole dish and smooth the top into an even layer. A flat surface gives the topping an even layer and helps the center bake at the same pace as the edges.

For the Pecan Topping:

• Stir together the toasted pecans, melted vegan butter or ghee, sweetener, almond meal, cinnamon, vanilla, and nutmeg, then scatter the mixture over the filling. Make sure the pecans cover the surface evenly, with no large bare patches of filling.
• Bake at 350 °F for 25-30 minutes, then remove the casserole and let it stand for 5 minutes. The center should jiggle only slightly when the dish is nudged, and the pecans should be golden brown and fragrant.
• Spoon the casserole onto plates while it is warm. The brief rest gives the custard center time to settle for cleaner portions beneath the crisp topping.