On a floured work surface, roll out the chilled dough into a 12-inch round. Transfer to a baking sheet lined with parchment paper. Spread the ricotta mixture evenly over the dough, leaving a 2-inch border. Lay the zucchini slices on top of the ricotta in concentric circles, starting at the outer edge. Drizzle with the tablespoon of olive oil. Fold the border over the filling, pleating the edge to make it fit. Brush crust with egg yolk.