Start by mixing graham cracker crumbs, granulated sugar, and melted butter in a large bowl until the mixture resembles wet sand. Press this mixture evenly into the bottom of a greased springform pan, creating a firm crust. Reserve the crust while you move on to the next step.

Boil water and pour it over the Earl Grey tea bags in a separate bowl. Let the tea steep for about 10 minutes, allowing the delightful floral notes to infuse into the water. After steeping, remove the tea bags and let the brewed tea cool completely before adding it to the cheesecake filling in the following steps.

In a mixing bowl, beat the softened cream cheese and granulated sugar together until smooth and creamy, which should take about 2-3 minutes. Add in the cooled Earl Grey tea, vanilla extract, and sour cream, mixing thoroughly until combined. Then, incorporate the eggs one at a time, ensuring each egg is fully integrated before adding the next. The filling should be smooth and free of lumps.

Preheat your oven to 325°F (160°C). Carefully pour the cheesecake filling over the prepared crust, spreading it evenly. Bake for 55-60 minutes, watching for the edges to set while the center remains slightly jiggly.

Once baked, remove the cheesecake from the oven and let it cool at room temperature for about 1 hour. Afterward, cover the cheesecake with plastic wrap and refrigerate for at least 4 hours or overnight, allowing it to set and develop its rich flavors.

While the cheesecake chills, prepare the mulberry sauce by combining mulberries, water, granulated sugar, and lemon juice in a small saucepan over medium heat. Simmer the mixture for about 10-12 minutes, stirring occasionally until it thickens and becomes jammy. Remove from heat and let the sauce cool before using it as a topping.

When ready to serve, carefully remove the cheesecake from the springform pan and place it on a serving platter. Generously spoon the cooled mulberry sauce over the cheesecake. Slice into pieces and enjoy the harmonious blend of flavors.