For the butter crust:
In a food processor, mix all the ingredients until the dough starts to form.
Press the dough into the bottom of an 8-inch (20cm) square baking dish lined with parchment paper.
Bake in the center of a preheated oven at 325°F (160°C) for 25 minutes or until the crust is golden brown and firm to the touch.

For the lemon and ginger filling:
In a bowl, using a whisk, beat the eggs and powdered sugar until the mixture is smooth and light.
Add the lemon zest, lemon juice, flour, and ginger until the mixture is homogeneous.

Pour the mixture over the crust.
Bake in the center of a preheated oven at 300°F (150°C) for 35-40 minutes.
Let cool completely on a wire rack before cutting into squares.
Sprinkle with powdered sugar and enjoy very fresh.