Preheat the oven to 180 ° C.
Rinse the quails inside and out and clean and pat dry. Sprinkle salt and pepper in the belly and on the outside. Wrap each quail in a pancetta slice and wrap a piece of kitchen string around it to secure it.
Melt the butter with the olive foil in a frying pan. Put the sage in the pan. Roast the quail over high heat until they have a nice golden brown color. Remove from pan and put in a baking dish. Add half of the grapes. Deglaze the pan with the marsala and broth.
Pour the contents of the pan over the quails, cover with aluminum foil and put the dish in the oven for 20 minutes. Add the remaining grapes for the last 5 minutes.
Remove the dish from the oven. Pour the broth into a pan. If necessary, boil it a little and season with salt and pepper.
Let the quails loosely covered with aluminum foil in a warm place for 5 minutes. Bake the crostini in a little butter until golden brown.
Cut the quail in half. Place a crostino on each plate, two quarters and some grapes. Pour the sauce over it.