In the bowl of a stand mixer, combine the ingredients for the dough and mix until the dough pulls away from the sides of the bowl. Sprinkle a little flour on your work surface to help you work with the dough.

Shape the dough into a long log about 20 inches (50 cm) long and cut it into 16 pieces. Let them rest for 30 minutes under a damp towel to prevent drying out.

Prepare the syrup by combining the water, sugar, and lemon slice in a pot. Boil for 5 minutes.

After the 30 minutes of resting, uncover the dough balls and sprinkle each with cornstarch.

Turn each ball over and press in the center with a rolling pin to flatten to about 8 inches (20 cm). Add more cornstarch as needed to prevent sticking.

Switch to a thin rolling pin and roll each piece of dough out as thin as possible, larger than your baking pan if you can.

Use your baking pan as a guide to trim the phyllo sheets. Place the trimmed sheets in the pan, and add any leftover pieces as well. This way, you get two layers each time.

After 4 layers, add half the filling. After 8 layers, add the rest of the filling, then top with 4 more layers.

Carefully cut the baklava, pour melted butter evenly over the top, and bake at 350°F (180°C) with top and bottom heat for about 1 to 1 1/2 hours, until golden brown.

Once baked, pour cold syrup over the hot baklava.