In the bowl of a food processor, combine the flour and butter. Pulse until crumbly. While pulsing, slowly add the ice water, and pulse just until the dough comes together into a ball. If needed, add up to 2 more tablespoons of ice water, a tablespoon at a time. Place the dough on a sheet of plastic wrap and flatten into a disk. Wrap snugly in plastic wrap, then place in the freezer for 10 minutes.

Preheat the oven to 350˚F.

In a small bowl, whisk together the egg yolk and heavy cream. Transfer the dough onto a large piece of parchment paper, and roll it out into a 12x16-inch rectange. Trim the edges if necessary. Brush the dough with the egg and cream mixture, then evenly sprinkle with turbinado sugar and slivered almonds. Bake about 30 minutes, until golden brown. Place on a wire rack and allow to cool completely.

In a mixing bowl, combine the cherries, sugar, and lemon zest. Toss well and refrigerate for 1 hour.

When the pastry has cooled, spread the ricotta over the top. Gently spoon the cherry mixture over the ricotta, and serve.