Peel and chop the potatoes into even-sized chunks, place them in a large pot, cover with water, and bring to a boil. Cook for about 15-20 minutes until fork-tender. Drain and return to the pot. Add butter, milk, salt, and pepper, then mash until smooth.

In a separate pot, bring salted water to a boil, add black bean spaghetti, and cook according to package instructions (about 6-8 minutes). Drain and rinse under cold water. Set aside to cool slightly.

Preheat oven to 375°F (190°C). In a greased baking dish, spoon the mashed potatoes in an even layer. Smooth the top with a spatula.

Scatter the cooked black bean spaghetti evenly over the mashed potatoes to create a 'worm' effect.

Sprinkle crushed olives over the black bean spaghetti, mixing with paprika if desired.

Bake for about 25-30 minutes until the top is golden and slightly crispy.

Remove from the oven, let cool for a few minutes, and serve hot, garnished with remaining crushed olives.