Bring a large pot of water to a boil. Add perogies and cook stirring occasionally for 5 mins. Drain perogies and set aside.
Preheat oven to 375 F. Butter a square 9x9 square oven safe casserole dish.
In a large glass mixing bowl, whisk eggs and yogurt in a large bowl. Mix in ½ cup of the feta cheese, bacon, onions, oregano and season with salt and pepper.
Pour mixture in prepared casserole dish and carefully add perogies distributing evenly. Place in preheated oven and bake for 10 mins.
Carefully remove casserole from oven and sprinkle remaining ¼ cup of feta cheese over egg mixture
Place casserole back in the oven and bake until golden brown and center is set, 25-30 minutes.