In a food processor, add in the butter, cream cheese, flour, granulated sugar and salt. Pulse until a dough ball forms.
Scrape the dough out onto the center of a piece of plastic wrap. Shape the dough into a disc. Cover the dough with the rest of the piece of plastic wrap and place into the fridge for about 30 minutes.
Work on the filling while the dough is chilling.
Preheat oven to 375 degrees. Butter 2 8 oz. ramekins or 4 4 oz. ramekins.
Place 1 cup of the strawberries into the cleaned out food processor. You don't want any dough crumbs left in it!
Add in the sugar, cornstarch, and vanilla. Pulse until the strawberries are completely pureed.
Pour the strawberry puree into a mixing bowl and add in the remaining 2 cups of quartered strawberries. Stir to combine. Set aside to finish the pie crust.
Place the chilled dough on a clean and floured surface. Roll the dough out to 1/4 inch thick. Measure out your ramekins and use a cutter or cup a similar size or slightly bigger. Cut out circles of pie crust.
Pour the strawberry filling into the prepared ramekins. Top each ramekin with a round pie crust.
In a small dish, whisk the egg and water to form a egg wash. Brush the egg wash onto the pie crusts.
Sprinkle the crusts with sanding sugar.
Place the ramekins on a tin foil lined cookie sheet with edges. Place into the preheated oven for 25 - 30 minutes (4 oz ramekins) or 35 - 40 (8 oz. ramekins) or until the crust is golden brown and the filling is bubbling out.