Preheat the oven

• Preheat the oven to 180 °C and line a baking dish with parchment paper.

Make the cookie dough

• Cream the softened butter with the granulated sugar until light and fluffy.
• Beat in the egg and vanilla extract.
• Add the flour, baking powder and salt and mix until a soft dough forms.

Bake the bars

• Press the dough evenly into the prepared baking dish.
• Bake until the edges are lightly golden and the center is set.

Make the frosting

• Beat the softened butter with the powdered sugar, milk and food coloring until smooth and spreadable.

Frost and decorate

• Let the bars cool completely, then spread the frosting over the top.
• Scatter the sprinkles over the frosting and cut into squares.