Preheat oven to 400 degrees F (204 C) and lightly grease (or line with parchment paper) 2 large, rimmed baking sheets (use fewer or more baking sheets, as needed, if altering batch size). Also lightly grease a small baking dish (8x8 inch is ideal // size as original recipe is written // adjust if altering batch size)).
Add halved sweet potatoes to one baking sheet, and the cubed butternut squash to another. Drizzle each with half of the avocado or melted coconut oil (1 Tbsp as original recipe is written // adjust if altering batch size).
Transfer mashed squash and potatoes to prepared baking dish and top with toasted pecans. Add vegan butter, cubed, to add additional moisture and flavor (optional).
*Nutrition information is a rough estimate.