Preheat oven to 400 degrees F.
In a large food processor, mix together flour, sugar and sea salt, then add butter cubes and pulse until it resembles peas.
Add the crust mixture to a large bowl and add the water, kneading until dough comes together and form into a disc. Then wrap the dough disc in parchment paper and refrigerate for at least 30 minutes.
Meanwhile, add blueberries, sage, sugar, tapioca, lemon juice and nutmeg to a large bowl and set aside.
In another large bowl, make the topping by combining flour, rolled oats, granulated sugar, brown sugar, salt, nutmeg and butter cubes, then combine by hand until they look like crumbs.
Line a half sheet pan with If You Care Parchment Paper, then remove the pie crust disc from the refrigerator and press into the pan, making sure to cover everything, including edges.
Pour blueberry and sage filling into the crust and top with the topping and place in the oven for 45 minutes.