Using a food processor, add flour, brown sugar and salt; pulse until well combined.

Cut butter into small cubes and add to the food processor; pulse until a crumbly mixture forms.

Add ½ cup of water and pulse until well combined. Continue adding water 1 Tbsp at a time (and pulsing) until dough comes together in a ball.

Flatten dough into a disc and wrap with plastic wrap. Refrigerate for at least 2 hours. (Note: Dough can be made the day before and refrigerated overnight.)

Using a medium mixing bowl, cream together butter and sugar until light and fluffy (~2-3 minutes on medium speed).

Add egg and vanilla; mix on low speed until just combined.

Using a separate bowl, sift together flour, baking soda and baking powder. Add dry ingredients to the mixing bowl and mix on low speed until just combined. Set bowl aside.

Preheat oven to 375°F.

Working on a lightly floured surface, roll dough into a 12”x17” rectangle. Press dough into a 10”x15” baking pan. (Note: Take extra care to press dough into corners of the pan.)

Using a large bowl, add granulated sugar, brown sugar, cornstarch and lemon juice; stir until well combined. Add blueberries; stir until well coated. (Note: The filling will not completely cover the dough. As the pie bakes, the berries will burst and fill in the gaps.)

Using a slotted spoon, transfer blueberry mixture into prepared pan.

Drop pieces of sugar cookie dough evenly on top of the filling. Sprinkle top of pie generously with coarse sugar.

Bake for 43-45 minutes, or until sugar cookie crust is golden brown.

Let cool for 1 hour before slicing and serving with {optional} vanilla ice cream.