In a large bowl, cream together softened butter and granulated sugar until light and fluffy, about 2-3 minutes.

Add egg yolk and vanilla extract; mix until fully combined.

Gradually add flour and salt, mixing on low speed until a soft dough forms. Do not overmix.

Divide dough in half, shape into discs, wrap in plastic, and chill for at least 30 minutes.

Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.

Roll out dough to 0.25-inch thickness on a lightly floured surface. Use flower-shaped cookie cutters to cut out cookies.

Place cookies 1 inch apart on prepared baking sheets. Bake for 10–12 minutes, or until edges are lightly golden.

Cool cookies completely on wire racks before decorating.

For royal icing: In a mixer, combine powdered sugar, meringue powder, water, and cream of tartar. Beat on low until smooth, then increase to high and whip for 5–7 minutes until stiff peaks form.

Divide icing into small bowls and tint with food coloring. Transfer to piping bags fitted with small round tips.

Outline each cookie with a thin line of icing, then flood the center with thinned icing. Use a toothpick to spread evenly.

Pipe petal details and centers using contrasting colors. Let dry completely (4–6 hours) before serving or storing.