Preheat your oven to 325°F (160°C). In a mixing bowl, combine graham cracker crumbs, granulated sugar, and melted butter until the mixture resembles wet sand. Firmly press this mixture into a greased 9-inch springform pan.

Bring a pot of water to a boil, remove it from heat, and steep the Earl Grey tea bags for about 10 minutes. Let the tea cool to room temperature.

In a large bowl, beat softened cream cheese and granulated sugar with an electric mixer until smooth. Gradually add cooled Earl Grey tea, vanilla extract, sour cream, and eggs; blend until combined.

Pour the filling over the prepared crust, smoothing the top with a spatula. Bake for 55-60 minutes until edges are set but center is slightly jiggly.

Turn off the oven and cool the cheesecake inside with the door slightly ajar for 1 hour. Then, refrigerate for at least 4 hours or overnight.

To prepare mulberry sauce, in a saucepan, combine mulberries, sugar, water, and lemon juice. Simmer for about 10-12 minutes until thickened.

Once cooled, remove the cheesecake from the springform pan. Slice and serve with warm mulberry sauce drizzled on top.