For the dough: In a large bowl, mix the flour, granulated sugar and salt. Using a pastry blender or your fingers, cut in the cold butter until pea-size.
In a separate bowl, beat the eggs with a fork until fluffy and pale yellow. Using a fork, mix the eggs into the flour mixture until the dough just comes together. Finish combining the dough with your hands to form a ball, being careful to avoid over-working the dough.
Cut the ball in half, forming two smaller balls of dough. Gently press down on each to form two equal disks. Wrap each disk in plastic wrap and place in the refrigerator for at least 2 hours or up to overnight.
For the filling: In a bowl, add the peaches, blueberries, brown sugar, flour, lemon juice and zest. Gently mix and set aside for 5 minutes.
For the topping: In a bowl, add the oats, brown sugar, butter, flour and cinnamon, and mix with your fingers, pinching the butter to create pea-size pieces.
Preheat the oven to 375 degrees F.
Lightly dust a clean surface with flour. Spray a 10-inch pie pan with nonstick cooking spray. Roll out the dough to about 12 inches in diameter, then place in the pan. Pour the filling over the dough and sprinkle the crumb topping over the top. Bake for 40 to 45 minutes. Cool on a wire rack before serving.
This recipe yields two portions of pie dough. Save the extra dough for another use.