1-Preheat the oven to 350°F (180°C) and grease and line a 9×13-inch baking pan with parchment paper to make removal easy later.

2-Cream the 225 grams unsalted butter and 300 grams granulated sugar together until they are light and fluffy, then add the 1 large egg and 1 teaspoon vanilla bean paste or vanilla extract, mixing well to combine.

3-Sift together the 320 grams all-purpose flour, 1 teaspoon kosher salt, and 0.25 teaspoon baking soda, then add this dry mixture to the wet ingredients and stir until just incorporated for a soft dough.

4-Spread the cookie dough evenly in the prepared pan and, if you like, sprinkle some extra granulated sugar on top for a bit of crunch.

5-Bake for 20 to 25 minutes until the bars are lightly golden and set, then let them cool completely in the pan on a wire rack.

6-For the frosting, whip the 170 grams unsalted butter, 1 teaspoon vanilla bean paste or vanilla extract, and 0.5 teaspoon salt until pale and creamy, then gradually add the 380 grams sifted powdered sugar and mix until smooth.

7-Add 2 tablespoons cream or milk a tablespoon at a time to get your desired frosting consistency, and if you’re feeling fancy, mix in some gel food coloring and whip on low speed for 2 3 minutes.

8-Spread the frosting evenly over the cooled bars, add sprinkles if desired, and chill until set for the best results.

9-For clean cuts, chill the bars slightly, use a sharp knife wiped between cuts, and consider using a ruler to portion them evenly into about 20 servings.