Preheat oven to 400°F. Line a baking sheet with parchment paper.
Heat a large pot over medium heat. Add butter and 2 tablespoons olive oil. When butter is melted and foamy, stir in onions and salt. Cover and cook 10 minutes, stirring occasionally until the onions soften.
Uncover the pot and turn heat to medium-high. Continue cooking the onions 20-30 minutes until they turn golden brown. Stir often to brown evenly.
Pour in wine and let boil until almost evaporated. Add garlic, flour and tomato paste; cook for 2 minutes.
Add broth and bring to a simmer. Cook 5 minutes, until soup is slightly thickened.
Place pierogies on the baking sheet and drizzle with remaining olive oil. Bake 15 minutes, turning over halfway through baking.
Sprinkle the cheese over the top of the pierogies and return to oven until cheese melts, 2-5 minutes.
Ladle soup into bowls and place baked pierogies on top.
Simple — and simply delicious. Smooth, creamy whipped potatoes, savory diced onions, and a perfect amount of salt and spices, wrapped up in a tasty pasta pocket.
Mrs. T’s Classic Onion Pierogies are simply satisfying sautéed in butter with a dollop of sour cream!