Preheat the oven to 400 degrees F (200 degrees C).
Place sweet potato on a cutting board. Place a chopstick on either side. Cut the sweet potato into 1/8-inch-thick slices, making sure you don't cut all the way through. Transfer to a baking pan.
Mix melted butter, maple syrup, cinnamon, and vanilla extract together. Spoon over the sweet potato.
Bake in the preheated oven until tender, 45 to 60 minutes.
Using your hands, make streusel by combining 2 tablespoons plus 2 teaspoons brown sugar, pecans, flour, butter, and salt. Keep refrigerated until ready to use.
Remove the sweet potato from the oven and sprinkle streusel over the top. Place in the broiler until streusel starts to brown, 1 to 3 minutes.