Preheat your oven to 350°F (175°C). In a mixing bowl, combine the graham cracker crumbs and melted butter until well blended. Press the mixture firmly into the bottom and up the sides of a 9-inch tart pan. Bake for 10 minutes, then remove from the oven and let cool completely.

In a small saucepan over medium heat, bring the heavy cream to a simmer. Remove from heat and add the chopped chocolate, stirring until smooth and fully melted.

Pour the chocolate ganache into the cooled tart crust, spreading it evenly. Allow it to set at room temperature for about 30 minutes, then refrigerate for at least 1 hour until firm.

Once the ganache is set, top the tart with fresh blueberries, arranging them evenly across the surface.

In a small bowl, whisk together the powdered sugar, vanilla extract, and a pinch of salt. Drizzle this mixture over the blueberries for added sweetness and flavor.

Slice the tart into wedges and serve chilled or at room temperature.