In a small bowl, stir together the cream cheese, 2 tablespoons sugar and the vanilla; refrigerate.
Using a food processor, pulse the flour, butter, salt and 1 teaspoon sugar until crumbly. Slowly add 3 tablespoons water, pulsing until the mixture forms a ball. Shape into a 5-inch disk, wrap in plastic wrap and refrigerate for at least 1 hour.
Preheat the oven to 400 degrees . On a floured work surface, let the dough stand unwrapped until softened, 10 minutes. Roll out 1/4 to 1/8 inch thick, then cut into 24 squares. Transfer to a baking sheet and refrigerate for 5 minutes. Place half of the squares on the floured work surface and brush the edges with water. Place a teaspoon of the cream cheese filling on each square. Cover with the remaining squares and seal. Transfer to the baking sheet and refrigerate for 15 minutes.
Bake the ravioli until golden, about 20 minutes. Let cool.
In a small saucepan, cook the remaining 1/4 cup sugar with 1/2 cup water over medium-high heat, until syrupy, about 5 minutes. Let cool, then stir in the mint and walnuts. To serve, top the ravioli with the mint sauce and the chocolate.