1. In a medium bowl, combine graham cracker crumbs, melted butter, and optional sugar; stir until crumbs are evenly moistened and resemble wet sand.

2. Divide crust mixture evenly among four 8-ounce mason jars or dessert cups; press firmly into the bottom of each jar using the back of a spoon or fingertips. Place jars in refrigerator to chill while preparing filling.

3. In a large mixing bowl, beat softened cream cheese with an electric mixer (or whisk) until smooth and creamy, with no lumps.

4. Add Greek yogurt, vanilla protein powder, powdered sugar (or chosen sweetener), vanilla extract, and lemon juice to the cream cheese.

5. Beat on medium speed until thoroughly combined and filling is smooth and fluffy; scrape down sides of bowl as needed. Taste and adjust sweetness or lemon tang if desired.

6. Spoon or pipe the cheesecake filling evenly over the chilled crusts in each jar; gently tap jars on counter to settle filling and remove air bubbles.

7. Cover jars with lids or plastic wrap; refrigerate for at least 4 hours, or preferably overnight, to set properly.

8. Before serving, top with fresh berries, whipped cream, chocolate shavings, or other desired toppings. Enjoy chilled.