Bring a large pot of water to a boil and add chopped sweet potatoes. We do not peel the sweet potatoes. Boil until potato chunks are tender, about 15 minutes. Pour potatoes into a colander to drain. Place chopped garlic on top of the hot potatoes to soften garlic.
Pour potatoes/garlic into a large bowl and mash by hand (using a mashing utensil) or use a hand held mixer. Add the olive oil and plant-based milk and mash until a preferred consistency is achieved. Stir in the salt and pepper to taste.
Preheat oven to 350°F (177°C). Spray a 9x13 baking dish with vegetable cooking spray.
Transfer the mashed sweet potato mixture to the prepared baking dish. Set aside.
For the Topping
In a bowl stir together the topping ingredients, except for the pecans. Stir until combined. Then add chopped pecans and stir until combined.
Sprinkle topping ingredients over mashed sweet potatoes in the casserole dish.
Bake for 35 to 40 minutes, until the topping is golden brown. Remove from the oven and cool for 10 minutes before serving.