1. Preheat your oven to 350 F (175 C). Line a 12-cup muffin tin with paper liners. In a medium bowl, combine the finely crushed graham crackers and melted butter. Mix until the crumbs are evenly moistened. Divide the mixture evenly among the muffin cups, pressing it firmly into the bottom of each liner to form the crust.

2. In a large mixing bowl, using an electric mixer, beat the softened cream cheese until it’s smooth and creamy, with no lumps. This usually takes about 1-2 minutes on medium speed.

3. Gradually add the granulated sugar (or sugar substitute) to the cream cheese, beating until well combined and fluffy. Then, mix in the fresh lemon juice, lemon zest, vanilla extract, and a pinch of salt until everything is thoroughly incorporated.

4. Reduce the mixer speed to low and add the Greek yogurt and vanilla protein powder. Mix until just combined and smooth. Be careful not to overmix at this stage, as overmixing can introduce too much air and cause the cheesecakes to crack during baking.

5. Divide the cheesecake filling evenly among the 12 muffin cups, spooning it over the graham cracker crusts. Fill each cup about two-thirds full.

6. Bake for 15-18 minutes, or until the edges are lightly set and the centers have a slight jiggle when gently shaken. Do not overbake, as they will continue to set as they cool.

7. Remove the muffin tin from the oven and let the cheesecake cups cool completely in the tin on a wire rack. Once cooled to room temperature, transfer the muffin tin to the refrigerator and chill for at least 2 hours, or preferably longer, until fully set. This chilling time is crucial for the texture.

8. Once thoroughly chilled, carefully remove the cheesecake cups from the muffin tin. Peel off the paper liners and serve.