Preheat your oven to 350°F (175°C) and grease a 9"x13" baking pan. In a large mixing bowl, combine the all-purpose flour, sugar, and salt. Using a pastry cutter or your fingers, cut in the cold unsalted butter until the mixture resembles coarse crumbs. Press the mixture evenly into the bottom of the prepared pan and bake for 20 minutes, until the edges are lightly golden.

While the crust bakes, whisk together sugar and flour in a separate bowl. Crack in the eggs, then add freshly grated lemon zest and juice. Mix until smooth. When the crust has cooled slightly, pour the lemon mixture evenly over it. Bake for an additional 20-25 minutes, until the filling is set but still slightly wobbles in the center.

Once the bars are out of the oven, let them cool at room temperature before transferring them to the fridge. Chill for at least 2-3 hours. Before serving, dust the top generously with powdered sugar and arrange fresh dandelion petals on top. Cut into squares and enjoy.