Prepare the crust: Preheat the oven to 350F. In a bowl, mix together the graham cracker crumbs, sugar and butter. Press into an 11-inch tart pan. Bake in the preheated oven for 6-8 minutes, or until golden brown. Remove and cool completely.
When the crust is cool, combine the lemon curd and the marshmallow creme in a bowl. Whisk until smooth. Pour into the cooled crust, and refrigerate until set up, at least a couple of hours. Serve with diced strawberries or with raspberries.