• Preheat the oven to 350°F. Grease a 9 x9-inch Square Baking pan.

To Make Bottom Crust

• In a Food Processor combine the confectioners' sugar, flour, butter, salt and thyme. Process the ingredients until it forms dough. If you are using cold butter this may take a few minutes. (Don't wash the bowl, we will use it again for the cream cheese dough.)
• Press the dough into the prepared pan. Lay a piece of plastic wrap over the top and then rub it smooth (remove plastic wrap before putting it in the oven!). Bake on the middle rack for about 20 minutes, just until it is light gold. Allow the crust to cool while you prepare the cream cheese dough and filling.

To Make Cream Cheese Lattice

• In the food processor cream together the cream cheese, butter and confectioners' sugar. Add the flour and pulse the dough until it comes together in a soft ball. Divide the ball in two discs and refrigerate for about one hour.
• If you are efficient, you can get away with using just one dough disc for the lattice, but sometimes I need to use a little bit of the second.

To Make Blueberry Filling

• Meanwhile, prepare the blueberries. In a sauce pan add the blueberries and ginger. In a small bowl whisk together the sugar and cornstarch, then add it to the blueberries. Cook over low heat until the blueberries thicken and reduce by about half. When you are done cooking them you will have about 2 1/2 cups of blueberry filling. Set aside while you prepare the lattice.

Assemble the Blueberry Bars

• Once the cream cheese dough is chilled, roll it out on a well floured surface and then use a Pastry Wheel to create strips. You can make them thick or thin, depending on what look you are going for. Mine were about about 1/2-inch thick.
• Lay out half the strips on a sheet of parchment, set on a cookie sheet, with some space between the strips. Fold up every other strip and lay one of the remaining strips across those still laid flat. Repeat with the next rows until you reach the bottom. Start back at the middle and do the same on the other side. Place the cookie sheet with lattice in the freezer to stiffen.
• Pour the blueberry filling over the thyme shortbread crust and let it sit while you wait for the lattice to chill. Remove the lattice from the freezer and make sure it is the right size. This is just done by eyeballing it next to the pan, then use the pastry wheel to trim excess. You can always trim more when you place it on the filling. Quickly brush the lattice with the egg wash.
• Carefully lift the lattice onto the filling. If the lattice is chilled well enough this should be a very easy task. If it is still too soft, return it to the freezer until it is harder. Trim any excess. Sprinkle with the sugar. Bake for about 35 to 40 minutes or until the crust is golden and the filling is bubbling.
• Allow the bars to cool completely. Trim the edges and cut into equal pieces. They can be stored at room temperature for a day and then covered and refrigerated or frozen.