Substitute plain, non-fat Greek yogurt for butter in your baked goods at a 1 to 1 ratio. For example, if your recipe calls for 1/2 cup of butter, you can safely substitute 1/2 cup of Greek yogurt; however, experts don't recommended that you this method for amounts over 1 cup. The yogurt increases the moisture content in the recipe, and too much can result in soggy muffins or cake. To avoid this problem, try increasing the flour in the recipe by about 1/4 cup or reducing the liquid in the recipe by approximately that same amount.

Another way to substitute Greek yogurt for butter in a baked goods recipe is to just replace half the butter with an equal amount of yogurt. In this case, for a muffin recipe that calls for 1 cup of butter, use 1/2 cup of Greek yogurt and keep the other 1/2 cup of butter. This, of course, does not reduce the fat content of the food by quite as much, but it reduces the risk of altering the texture of the final result.

Greek yogurt is often made from sheep’s milk, which has a different chemical composition than the cow’s milk from which butter is typically made. Sheep’s milk has less lactose than cow’s milk, so Greek yogurt is also a workable substitution for individuals who find lactose difficult to tolerate.

Baked goods that require melted butter can pose additional challenges when you try to substitute Greek yogurt. Because Greek yogurt is strained, it has a thicker, creamier texture than regular yogurt. Therefore, it acts much more like a solid than a liquid in a recipe, and substituting it for melted butter will result in a thicker cake batter or more dense bread dough. Increasing the amount of other liquids in the recipe slightly will help remedy this.