In a small bowl, combine crushed graham crackers with melted butter until evenly mixed. Firmly press this mixture into the bottom of a microwave-safe mug to create a compact crust.

In a separate bowl, beat together cream cheese, sugar, and vanilla extract until smooth and creamy, about 2-3 minutes. If using an egg, add it now and continue blending until pale and fluffy.

Carefully pour the cream cheese filling over the graham cracker crust in your mug, ensuring the filling covers the crust evenly.

Place the mug in the microwave and heat for 30-60 seconds, watching closely to avoid overcooking.

Once microwaved, let it cool for a few minutes at room temperature or refrigerate for 15-30 minutes for a denser texture.

When ready to enjoy, add toppings like whipped cream or fresh berries and savor each creamy bite.