Place the brick of feta and tomatoes into a small baking dish. Sprinkle with oregano, sugar and extra-virgin olive oil. Bake for 15-20 minutes, until tomatoes burst and feta is soft and edges turn golden brown.
While the feta is baking, cook pasta in a large pot of lightly salted water according to package directions for al dente. Reserve one cup of pasta water and drain the rest.
Place the baked feta, yogurt and pepperoncinis into a large skillet over medium heat. Stir until smooth. Slowly add the reserved pasta water until the desired consistency is achieved.Add the cooked pasta back in and coat with the feta sauce.
Before serving, stir in the spinach leaves until they wilt, 1-2 minutes. Garnish with the roasted tomatoes and freshly cracked black pepper.