01 - Preheat the oven to 375°F (190°C).
02 - In a large oven-safe skillet or Dutch oven, sauté the chopped onion and minced garlic over medium heat until softened. Add ground lamb, cumin, oregano, salt, and pepper. Cook, stirring occasionally, until the lamb is well browned and cooked through.
03 - Boil penne pasta in a large pot of salted water for about 6 minutes, until just shy of al dente. Drain well and set aside.
04 - In a mixing bowl, combine Greek yogurt, milk, lemon juice, grated and squeezed cucumber, fresh dill, and a pinch of salt. Stir until smooth and evenly blended.
05 - Add the par-cooked pasta, cherry tomatoes, black olives, and crumbled feta cheese to the cooked lamb mixture. Pour the prepared sauce over everything and gently stir to ensure even distribution. Top with extra feta or shredded mozzarella cheese as desired.
06 - Transfer the skillet or pot, uncovered, to the preheated oven. Bake for 20 to 25 minutes, or until the top is golden brown and bubbling.
07 - Remove from the oven and allow to cool slightly. Garnish with chopped fresh parsley if desired and serve warm.