In a large 12-inch skillet over medium heat, add the olive oil and the kielbasa and cook until crispy, stirring occasionally, about 5 minutes.
Add the pierogi and butter and let cook until the pierogi are nicely browned, about 3 to 5 more minutes.
Add the leek and cook until wilted, another 2 minutes, before pouring in the broth and creme fraiche.
Let gently simmer for another couple minutes before adding the chives; season with salt and pepper as desired.
