Butter tarts are a classic Canadian dessert made with a flaky pastry shell filled with a sweet, gooey mixture of butter, sugar, and eggs. They can be made with or without additional ingredients like raisins or nuts, which add different textures and flavors. The filling is typically baked until it is set but still slightly runny in the center. These tarts are often enjoyed warm or at room temperature and are a popular treat at Canadian gatherings and celebrations. Their origins date back to the 19th century, and they are considered a symbol of Canadian culinary heritage.