Preheat the oven to 350°F (175°C).

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

Add the egg and vanilla extract and mix until combined.

In a separate bowl, whisk together the all-purpose flour, baking powder, and salt. Gradually add the dry ingredients to the wet mixture, mixing until a soft dough forms.

Roll out the dough on a floured surface to about 1/4 inch thickness. Use a heart-shaped cookie cutter to cut out the cookies and place them on a baking sheet lined with parchment paper.

Bake for 10-12 minutes or until the edges of the cookies are lightly golden.

Allow the cookies to cool completely on a wire rack.

For the buttercream roses, beat the softened butter with powdered sugar. Add milk a little at a time until reaching the desired consistency.

Divide the buttercream into small bowls and add food coloring to each, mixing to create the desired colors for your roses.

Using a piping bag fitted with a petal tip, pipe small roses on top of each cooled cookie.

Allow the buttercream roses to set before serving.