Peel and chop large Yukon Gold potatoes, then place them in a pot of salted water. Bring to a boil and cook for about 25 minutes, or until the potatoes are tender and easily pierced with a fork. Drain the potatoes and let them cool slightly while you prepare the other ingredients for your creamy pierogi lasagna.

In a large skillet over medium heat, add chopped bacon and cook until crispy, which should take around 8-10 minutes. Using a slotted spoon, transfer the bacon to a plate, leaving the rendered fat in the skillet. Add sliced onions to the skillet and sauté them for about 5-7 minutes until they are golden and caramelized, stirring occasionally.

In a large bowl, combine the drained, slightly cooled potatoes with minced garlic, sour cream, butter, milk, and cream. Mash until smooth and creamy, ensuring there are no lumps. Season the mixture with salt to taste, creating a flavorful filling for your pierogi lasagna.

Prepare the lasagna noodles according to package instructions, but reduce the cooking time by about 5 minutes to keep them slightly firm. Once cooked, drain the noodles and toss them lightly in olive oil to prevent sticking as you assemble your dish.

In a deep baking dish, start layering your creamy pierogi lasagna. Begin with a spoonful of the potato filling on the bottom, followed by a layer of noodles, some crispy bacon, caramelized onions, and shredded cheddar cheese. Repeat these layers for about 4-5 times until all ingredients are used, finishing with a cheese layer on top.

Preheat your oven to 350°F (175°C). Cover the assembled lasagna with aluminum foil and bake it for approximately 30 minutes or until heated through and bubbly. If you prefer a crispy top, remove the foil in the last 10 minutes of baking to allow the cheese to brown nicely.

After removing the creamy pierogi lasagna from the oven, let it cool for about 10 minutes to help set the layers. Before serving, sprinkle the reserved crispy bacon and chopped scallions on top for a fresh, vibrant touch. Slice into squares and enjoy this delightful twist on a classic comfort food!