In a large bowl, beat the butter, sugar, and vanilla extract until creamy and smooth.

Add the egg and mix until fully incorporated.

Add the flour, baking powder, and salt to the wet mixture. Mix with a spatula or your hands until a smooth dough forms. Avoid overmixing.

Divide the dough into three portions: Portion 1: Leave uncolored (base dough). Portion 2: Add a few drops of red food coloring and mix until a soft pink tone is achieved. Portion 3: Add more red food coloring to achieve an intense red color.

Wrap each portion in plastic wrap, flattening slightly, and freeze for at least 3 hours or until firm.

Roll out the uncolored dough between parchment paper, using a bit of flour to prevent sticking, until it’s evenly thick. Set aside.

Repeat with the pink and red doughs.

Use a small heart-shaped cutter to cut multiple shapes from the pink and red doughs.

Place these small hearts onto the uncolored dough, alternating colors to create a mosaic effect.

Place parchment paper over the assembled dough and gently roll over it with a rolling pin to press the shapes together without distorting them.

Use a large heart-shaped cutter to cut the cookies. Transfer them to a baking sheet lined with parchment paper or a silicone mat.

Place the cut cookies in the freezer for 5 minutes to help them hold their shape during baking.

Preheat the oven to 350 °F (180 °C).

Bake the cookies for 7–8 minutes, or until the edges are firm but not browned.

Let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.