Preheat oven to 350º F. Line the bottom of a springform pan with foil, folding it up at least 3 inches to prevent water from seeping into the pan. Set aside.
Process the graham crackers into crumbs using a food processor.
Add the melted butter to the graham cracker crumbs, and pulse a few times to mix into the crumbs.
Press the mixture into the bottom of the springform pan. Press the crumbs down firmly to form the crust, and then set aside.
Prepare the cheesecake batter by adding the room temperature cream cheese to the food processor. Process to soften the cream cheese, stopping to scrape the sides of the processor bowl with a rubber spatula a few times.
Once the cream cheese is soft and creamy, add the Greek yogurt, maple syrup, lemon juice, vanilla extract, optional lemon extract, and lemon zest. Process to blend it together, without over mixing, scraping the sides as necessary.
Add the eggs, 1 at a time, pulsing to mix in each one before adding the next egg. Again, be cautious not to over process and add too much air to the mixture.
Pour the cheesecake batter into the spring form pan on top of the crust.
Pour 2-3 inches of boiling water into a roasting pan. Place the springform pan with prepared lemon cheesecake into the water.
Bake lemon cheesecake for 55-70 minutes, until the center of the cheesecake is fully set.
Turn the oven off and allow heat to escape from the oven (for about 1 full minute). Close the oven door and allow the baked cheesecake to cool in the oven for 1 hour.
Allow the cheesecake to cool at room temperature for 1 hour prior to placing it in the refrigerator to cool before serving.