Preheat oven to 350°F (175°C).
Heat oil in a pan and sauté garlic and onion until fragrant.
Stir in crushed tomatoes, paprika, and oregano. Simmer for 8 minutes, then remove from heat.
Boil cassava until fork-tender. Remove the fibrous core.
Mash cassava with butter and milk until smooth. Add more milk or butter as needed.
Boil sweet potatoes until tender. Drain and mash until smooth.
In a greased baking dish, layer in this order: mashed cassava, mashed sweet potatoes, then the tomato sauce.
Top with grated cheese.
Bake for 40 minutes until bubbly and golden.
Remove from oven, cool slightly, and serve.