Prepare All-Butter Pie Crust. Mix flour, sugar, and salt in a large bowl. Remove 2 tablespoons of butter and reserve then cube the remaining cold butter into small pieces. Cut in using fingertips or a food processor until only pea-sized pieces remain. Sprinkle with water, 3 tablespoons at a time, while tossing lightly just until dough comes together. Divide dough in half. Wrap in plastic and chill at least 30 minutes or up to 5 days.
Zest lemon then juice, reserve 1 tablespoon lemon juice for filling and add remaining juice to a large bowl of cold water with lemon halves.
Bring a large pot of water to a simmer of medium-high heat and place the lemon water nearby. Quickly dunk pears in hot water for 10-15 seconds only. Then, immediately place into the cold lemon water and rub skin off. Remove pears and blot dry with paper towels.
After peeling pears, measure the height and slice the tops off five of the pears to peak out of the lattice crust later. Cut the remaining pear and the five bottoms into large chunks (will be about 4 cups) and mix with sugar, cornstarch, flour, a pinch of salt, lemon juice and zest, ground ginger and the frozen forest berries.
On a lightly floured work surface, roll out 1 disk of dough to an 12-inch round- turning the dough about a quarter turn after every few rolls to prevent it from sticking and keep it even. Fit the dough into a 10-inch pie pan without stretching and place in fridge to chill. Then, roll the other flat and chill on a floured sheet pan.
Place a layer of PearBerry filling into chilled pie shell. Nestle the pear tops into the filling so they stand straight up, with 1 in the middle and 4 around it.
Spoon remaining filling around pears and dot with reserved Plugrá® Butter.
Cut strips from chilled crust, arrange around the pear tops in a rough lattice-type pattern, and press all around the edge to seal. Trim any overhang, fold strips over the rim of the bottom crust, and make a solid seal. Crimp in a decorative pattern.
Preheat oven to 425 degrees and place pie in the fridge to chill, up to 20 minutes.
Beat egg with cold water then brush on crust, avoiding the outer edge and sprinkle with coarse sugar.
Place on baking sheet and bake in the center of preheated oven for 20 minutes.
Drop oven temp to 375 F and continue baking until juices bubble thickly and crust is deep golden, covering with foil if edges or pear stems are browning too quickly, 45-60 minutes longer.
Cool on a rack, about 3 hours. Serve warm or at room temp with a drizzle of wildflower honey and vanilla bean ice cream.
Cover leftovers tightly and store in the refrigerator for up to 5 days. Or wrap and freeze for up to 3 months.