Preheat the oven to 400 degrees F.
Arrange the pears, cut sides up, on a baking sheet and dot with butter. Put the baking sheet in the oven and bake 25 to 30 minutes, or until the pears are just tender. Let cool.
Increase the oven heat to 450 degrees F.
Sprinkle the counter and a rolling pin lightly with flour. Roll the dough out to a 14-inch round, about 1/4-inch thick. It doesn't have to be perfect. Transfer the dough to the back of a lightly floured baking sheet. Slice the pears and arrange them on the dough round by overlapping the slices in a spiral fashion, leaving a 2-inch border all around. Drizzle with the honey, scatter blue cheese over the top, and sprinkle with the almonds.
Brush the border with the egg wash. Bring the edge of crust over onto the filling, leaving the fruit exposed in center. Gently fold and pinch the dough to seal any cracks. Brush the crust with the remaining egg wash and sprinkle with the sugar. Put the baking sheet in the oven and bake for 30 minutes or until the crust is golden brown and the fruit is tender. Slide a knife under the crostata to loosen it from the pan. Then cut into wedges and serve warm or at room temperature.
Combine the flour, sugar, salt, and lemon zest in a large mixing bowl. Add the butter and mix with a pastry blender or your fingers until the mixture resembles coarse crumbs. Add the egg yolk and ice water and work that in with your hands. (Or do the whole thing in a food processor, pulsing a couple of times to combine the dry ingredients, then pulsing in the butter, and then the egg.) Check the consistency of the dough by squeezing a small amount together between thumb and forefingers: You want there to be just enough moisture to bind the dough so that it holds together without being too wet or sticky. If it's still crumbly, add a little more ice water, 1 teaspoon at a time. When you get it to the right consistency, shape the dough into a disk and wrap it in plastic. Put it in the refrigerator and chill for at least 30 minutes.