1. If using unsweetened yogurt, first whisk in the powdered sweetener.
2. Spread about a fourth of the yogurt evenly into the bottom of an 8 inch square pan.
3. Break the graham crackers or cookies into large pieces (see video for a visual), and arrange in a layer above the yogurt.
4. Add a layer of sliced berries if desired. Then top with a second layer of yogurt.
5. Repeat with alternating layers of graham crackers, berries, and yogurt.
6. Cover loosely, making sure to leave an opening for moisture to escape. Refrigerate eight hours or overnight. The breakfast yogurt cheesecake will thicken and firm up as it chills.
7. Slice and enjoy for breakfast, snack, or dessert.
8. Tightly cover any leftovers after a day, and refrigerate for up to a week. Or freeze for up to three months and thaw before serving.