Prepare the pie crust and shape half of the dough into a 9" pie plate. Top with plastic wrap and place in the fridge.
1 Double Crust
Wrap the other half in plastic wrap and then in a ziplock bag and store in the fridge or freezer for another pie.
Preheat the oven to 375 degrees.
Add 3/4 the fruit, sugar and Ultra Gel into a saucepan and gently, using a rubber spatula, fold the berries in. Start with only 1/2 cup sugar, but if your berries are extra tart you should add more sugar, 1 tablespoon at a time. Turn the heat to medium low and cook until the berries are releasing their juices and beginning to thicken. Only stir occasionally as you don't want to break up the fruit and turn it into jam.
2 Pints Raspberries, 2 Pints Blackberries, 1 Pint Blueberries, 1/2 - 3/4 Cup Sugar, 1/4 Cup [Cornaby's Ultra Gel]
Allow the fruit to cool.
Prepare the Topping
In a large bowl, mix together the flour, cinnamon, oats, brown sugar and salt. Cut in the butter using a pastry cutter or your hands.
1 Cup Flour, 1 teaspoon Cinnamon, 1 1/2 Cups Old Fashioned Oats, 1 1/2 Cups Light Brown Sugar, 3/4 Cup Unsalted Butter, 1/8 teaspoon Salt
Stir in the remaining berries and pour into the pie crust. Sprinkle the topping all over the top.
Bake the pie for 25 minutes then drape with a piece of tin foil and continue to bake for another 20-30 minutes, or until the filling is bubbly and the crust is golden brown.
Remove from the oven and cool entirely on the counter. We prefer to let our pie rest over night as the filling will set up and not run. Place in the fridge to cool faster if needed, but remove to the counter to come back to temperature before serving.
Notes
Pie can be assembled and frozen before baking. A frozen pie will keep for 3-6 months.If you can find marionberries in the freezer section use those in place of all the berries.