In advance, make puddle dots. Prepare color flow icing and divide in thirds. Tint 1/3 dark rose, 1/3 light rose, leave 1/3 white. Using tip 3 and thinned color flow, pipe 1/2 in. puddle dots onto waxed paper-covered board. Make 100 each white and dark rose, 110 light rose. Make additional dots to allow for breakage. Let dry overnight. When dry, brush dots with Pearl Dust.
Bake and cool 2-layer heart cake (bake two 1 1/2 in. high layers for a 3 in. high cake). Ice cake smooth with light rose buttercream.
Position dots on cake top in a heart shape, placing light rose at outer edge, then white, then dark rose at center.
Using smooth side of tip 2B, pipe rose buttercream bottom border. Attach remaining dark rose dots, 1 3/4 in. apart.