In a food processor, add the flour, cornstarch, salt, and thyme. Pulse a few times to combine. Add in the butter about 1/3 at a time and pulse in between additions a few times to make sure it is evenly distributed. After all the butter is added, pulse until very small crumbs are formed. Add the egg and pulse until incorporated, the mixture will not resemble a dough ball but when pinched together it will stay.
On a clean work surface, gather the dough into a ball, press it into a 9-inch tart shell all the way up the sides of the pan. Place in the fridge for 30 minutes.
For the filling
Preheat the oven to 375°F. Spread the softened cream cheese into the bottom of the tart. Top with the tomato slices in whatever pattern you like. Sprinkle on the gorgonzola cheese and thyme.
Bake for 35 minutes until the crust is golden brown and slightly pulling away from the edges. Let cool on a wired rack for at least 10 minutes. Garnish with the olive oil and serve!