Place the flour on a worktable. Make a well in the center of the flour and add the olive oil, yeast, eggs, 1/4 cup sugar, grappa, and 1/2 the grapes. Combine the ingredients together and knead until the mixture becomes an even dough. If necessary, add a little more flour to absorb all the liquids.
Roll out the dough to a 1/2-inch thickness. Line a baking tray with parchment paper and spread the dough on the tray. Add the remaining grapes and squish some of the grapes to release the juices, while leaving the others whole. Sprinkle the remaining 1/2 cup sugar and drizzle with olive oil.