Preheat your oven to 180°C (350°F) and grease a baking pan (8x8 inch or similar size) or line it with parchment paper for easy removal of the bars.

In a large mixing bowl, beat together 170 g of softened butter and 70 g of powdered sugar until light and fluffy. You can use an electric mixer or a whisk for this.

Add 1 egg and 8 g of vanilla sugar to the butter and sugar mixture, and beat until fully combined.

Gradually add 250 g of flour (about 2 cups) into the mixture, stirring until a dough forms. The dough should be soft but not sticky.

Press the dough evenly into the prepared baking pan, creating a smooth, even layer. Use your hands or the back of a spoon to press it down firmly.

Set the pan aside while you prepare the peanut filling.

In another bowl, combine 2 cups of roasted grated peanuts and 1/2 cup of sugar. Stir until the sugar is evenly distributed throughout the peanuts.

Add 3 tablespoons of melted butter, 2 eggs, and 8 g of vanilla sugar to the peanut mixture. Stir until everything is well incorporated.

Grate the zest of one lemon into the mixture and stir to distribute the zest evenly, adding a bright citrus note to the filling.

Finally, add 1 tablespoon of flour and 5 g (1 tsp) of baking powder, mixing until the filling is smooth and slightly thickened.

Pour the peanut filling over the shortbread base, spreading it evenly to cover the entire surface of the dough.

Once assembled, place the baking pan in the preheated oven and bake for 30 minutes at 180°C (350°F). The peanut layer should become slightly golden, and the shortbread base should be cooked through.

After baking, remove the pan from the oven and allow the bars to cool completely in the pan.

Once the bars are cooled, melt the chocolate in a microwave-safe bowl or over a double boiler. You can use dark, milk, or semi-sweet chocolate depending on your preference.

Drizzle the melted chocolate over the top of the cooled peanut bars in a zigzag pattern, or pour a layer of melted chocolate over the entire surface if you prefer a richer topping.

Let the chocolate set by leaving the bars at room temperature or placing them in the refrigerator for quicker results.

Once the chocolate has hardened, carefully slice the bars into squares or rectangles. Serve the bars at room temperature, and enjoy the combination of buttery shortbread, nutty peanut filling, and smooth chocolate.