Whisk the flour, baking powder, and salt together in one bowl.
Cream the softened butter and granulated sugar in a separate bowl until the mixture is light and fluffy, about 2 to 3 minutes.
Add the egg and vanilla extract to the butter mixture and mix until smooth.
Gradually add the dry ingredients to the wet ingredients until the dough forms.
Wrap the dough and chill it for a minimum of 1 hour.
Roll the dough to 1/4 inch thickness. Cut small shapes, such as flowers or circles.
Place the cut shapes on a lined baking sheet. Bake at 175°C for 8 to 10 minutes, or until the edges are set.
Remove the cookies from the oven and cool them completely.
Prepare the royal icing by mixing the powdered sugar, meringue powder, and water until the mixture is smooth and glossy.
Divide the icing and tint it with pastel colors using gel food coloring.
Use piping bags with fine tips to outline and flood the cookies with the base icing layer.
Let the base layer dry for 4 to 6 hours.
Pipe small floral details, such as dots, petals, or leaves, using thicker icing.
Allow the cookies to dry fully before you serve or package them.