Taking A Snow Town, 1891
Yes, Butter Week, or Butter Lady, Crepe Week or Cheesefare Week, or in Russian, Ukrainian and Belorussian respectively; Мaсленица, Масниця, Масленіца.
What is Maslenitsa?
Well, earlier this past week we discussed Clean Monday, the first full day of Great Lent for the Eastern Rite, including those who are Eastern Rite Catholics and Eastern Orthodox observing the "old Calendar" in liturgical terms. For those in the Eastern Rite who are in the new calendar, which this past Monday would have been part of, this week was last week. In other words, for those Eastern Rite on the old calendar, Clean Monday is this upcoming Monday and Great Lent starts tomorrow.
Maslenitsa is, therefore, sort of a week long Slavic Mardi Gras and indeed shares the connection with the same set of foods, fats, and stuff made with them.
And it was also a week long celebration, as the pre Lenten celebrations are to some extent in some Latin Rite countries. Except, appropriate for its region, it featured traditionally a lot of winter games.
Of course, the Communists put a damper on all of this, given its religious nature, but it never went away. And as Christianity has revived in the Slavic regions following the downfall of Communism, it's religious nature and the tradition is reviving.