Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a medium bowl, whisk together the all-purpose flour, baking powder, and salt until combined.

In a large bowl, beat the softened unsalted butter and granulated sugar together until light and fluffy.

Beat in the egg and vanilla extract until well combined.

Gradually add the dry ingredients to the butter mixture, mixing until a smooth dough forms.

Divide the dough into two portions, flatten each into discs, wrap in plastic wrap, and refrigerate for at least 30 minutes.

Roll out the chilled dough to about 1/4-inch thickness on a lightly floured surface and cut out your cookies with a heart-shaped cookie cutter.

Place the cookies on the prepared baking sheet and bake for 8-10 minutes, or until the edges are lightly golden.

Let the cookies cool on a wire rack.

Beat the egg whites until soft peaks form.

Gradually add powdered sugar and continue beating until stiff peaks form.

Add vanilla or almond extract and mix well.

Divide the royal icing and add food coloring for desired hues.

Flood the cooled cookies with the colored royal icing and let set for 15-20 minutes.

Use the white icing for piping decorative details as desired.

Roll out colored fondant and use flower-shaped cutters to create flower shapes.

Press fondant shapes into the royal icing for added decoration.

Let the cookies dry completely for 1-2 hours before serving or packaging.