Preheat the oven to 400ºF. Spray an 8x8-inch baking dish with cooking spray. Set aside.
Spray a baking sheet with cooking spray (or line it with foil and spray the foil with cooking spray). Peel the sweet potatoes and chop them into 2-inch cubes. Place them onto the prepared baking sheet. Drizzle with olive oil and toss to coat the potatoes.
Bake until tender, about 25 minutes. Toss halfway through baking.
While the sweet potatoes are baking, make the topping. Place all of the topping ingredients (except the bacon) into a large food processor. Pulse on high until the mixture forms a crumble.
Add the diced bacon to the food processor and pulse a couple more times to incorporate the bacon bits into the mixture. Transfer the crumble to a separate bowl.
Once the potatoes are cooked reduce the oven temperature to 350ºF. Transfer the potatoes to the same food processor you used for the pecan mixture. Add the almond milk, yogurt, and salt. Use the pulse feature to combine the ingredients, but do not totally purée the sweet potato. You want some chunks.
Once mashed, transfer the sweet potato mixture to the baking dish. Use a spatula to evenly spread it out. Sprinkle the pecan mixture on top.
Bake the casserole for 25 minutes. For a crispier topping, broil the sweet potato casserole for an additional 4-5 minutes.