The phrase "butter extract" refers to a concentrated flavoring made from real butter. It is used to give a taste of butter to dishes or baked goods without actually using butter. Full definition
With a healthy dose of chocolate chips and natural butter extract, these healthy cookies become as tempting as any other! (naturalsweetrecipes.com)
You could also use regular butter, ghee (clarified butter), or coconut butter with a quarter teaspoon of butter extract, but doing so will nearly double the calories from fat. (noexcusesnutrition.com)