This is the ultimate pie to feed a crowd! Be sure to use tart (also known as "sour") cherries for this pie. Keep the cherry slab pie loosely covered with wax paper at room temperature and it will stay nice for a two- to three days.
Place an over rack in the center of the oven, and heat the oven to 375 degrees.
In a medium heavy pot, cook the cherries over medium high heat until the cherries have burst and released their juices, about 10 minutes. Add the sugar and cornstarch and cook over medium heat until thickened. Stir in the lime juice, lime zest, almond extract and rose water. Set the filling aside.
Make the dough in a large bowl. Whisk the flour and salt to combine. Add the oil and stir just until combined. Add the ice water and cut the water into the dough using the side of a large metal spoon. Less handling is better here. The dough will appear streaky with areas that are more hydrated than others; this is correct.
Roll out the dough between sheets of wax paper. Cut four sheets of wax paper the length of a half sheet pan (which is about 18 x 13 inches). Wipe down the work surface with a sponge that has been dipped in cold water and wrung out (in other words, not too much water on the counter, just enough to hold the wax paper in place).
Lay a sheet of the wax paper on the damp counter, and shape just over half of the dough into a rectangle. Top with another sheet of wax paper, and roll out a rectangle just a bit larger than the sheet pan to account for the crust coming up the sides of the rimmed pan. Pull the top sheet of wax paper off the rolled dough, then use the bottom sheet to move and flip the dough onto the sheet pan, arranging it before carefully peeling the wax paper from the dough.
Tuck the dough into the pan. Cut scraps from the areas where the dough may be too large, and use those scraps to make up for short areas of dough around the pan by pushing the scraps into the short or open areas.
Spoon and scrape the cherry filling from the pot into the dough-lined pan in a single layer of cherries.
Roll out the top layer of the crust in the same manner as the bottom layer, but not quite as large as this piece does not need to come up the sides as the bottom layer did. Peel off the top piece of wax paper, and use the bottom piece to flip and arrange the top crust dough over the cherries. Peel the wax paper from the top crust.
Seal the edges of the top and bottom crust around the perimeter of the pan. Using your fingers, rub the heavy cream over the top of the crust. Prick the crust here and there with the tines of a fork.
Bake the pie for 40 minutes. While the pie bakes, make the lime sugar by rubbing the zest of a lime with 4 tablespoons of sugar, until the sugar is damp and the lime oil is released. Immediately after removing the pie from the oven, dust with the lime sugar.
Cool the pie completely before cutting and serving.