Roll out the prepared pie dough into a circle. Just eyeball your pie plate and the circle to see if you're close. That's my technique.
Once your circle is about the size you need, fold the dough in half and pick it up and place onto the pie plate. Unfold the dough and push the dough onto the bottom and sides.
Trim the edges. I cut them even with the edge of the pie plate using a knife.
In a large mixing bowl, add in the sliced pears, blackberries, granulated and brown sugar, cinnamon and flour. Stir to combine and make sure all the fruit is coated.
Pour the fruit into the pie shell.
Repeat the rolling out with the top piece of dough.
In a small bowl, crack the egg and beat it. Using a pastry brush, rub the egg wash onto the bottom edge of the pie crust.
Lay the top layer of dough on. Cut some steam holes into the top layer. You can cut the steam holes before you place the dough on the pie or after. I do it after so I can keep them sort of centered.
With your forefinger and thumb, crimp the pie crust together. I usually form a "U" with my forefinger and thumb on the inside of the edge. With my other forefinger, I push the dough between my thumb and forefinger resting on the inside. (I hope this helps)
With the pastry brush, cover the top layer with the egg wash.
Place into the at 425 degrees for 20 minutes and then turn the heat down to 350 and bake another 40 minutes. The pie will be bubbly and brown.