Preheat oven to 400 degrees.

Line baking sheet with parchment paper and reserve.

In a mixing bowl, sift together flour, sugar, baking powder, baking soda, and salt. Cut in butter using a pastry cutter. Mixture will resemble coarse meal.

In another bowl, combine egg, sour cream, vanilla and water. Beat lightly with a fork. Add to flour mixture, stirring with fork to make a shaggy dough. Add the marshmallows, chocolate chips and vanilla wafers. Pour out onto a clean surface and knead about 10 to 15 times, until it just comes together.

Pat out into a 1-inch thick circle. Use a pizza cutter to cut into 16 wedges. Transfer to parchment lined baking sheet, brush with egg wash.

Bake for 12-15 minutes. Serve warm or room temperature.