- Preheat oven to 350F. Lightly oil or spray 4 6-in. round cake pans and line bottoms with parchment.
- Stir flour with baking powder and salt in medium bowl. Beat butter with granulated sugar in large bowl, with an electric mixer on medium, until fluffy. Add eggs, 1 at a time, beating well and scraping down sides of bowl as needed. Beat in 1 tsp vanilla. Reduce speed and beat in one- third of flour mixture, then add half the milk. Repeat, ending with flour mixture.
- Divide batter into 4 bowls (about 1 cup each). Set 1 portion aside (do not colour). Add varying amounts of food colouring to remaining 3 portions, to create 3 shades of pink. Scrape each bowl of batter into a prepared pan.
- Bake in centre of oven until a cake tester inserted in centre of cakes comes out clean, 20 to 25 min. Cool in pans on a rack for 10 min, then turn cakes out onto rack. Remove parchment. Cool completely, about 30 min.
- Beat 1 cup butter in a large bowl, with an electric mixer on medium, until creamy, 1 min. Add 1 tsp vanilla and 1 cup icing sugar. Beat for 1 min. Reduce speed and beat in remaining sugar in 3 parts, alternating with milk (in 2 parts) and ending with sugar. Beat on medium-high, scraping down sides of bowl as needed, until fluffy and smooth, 1 to 2 min.
- Assemble cake by setting the darkest pink layer on a cake stand. Lay short strips of parchment under edges of cake to protect the stand. Spread with 1/2 cup icing. Continue with remaining layers and icing, with white layer on top. Spread a thin layer of icing on sides and top of cake. Refrigerate until icing is firm, about 15 min.
- Divide remaining icing into 4 bowls. Set 1 portion aside (do not colour). Add varying amounts of food colouring to remaining 3 portions, to create 3 shades of pink. Spread the darkest pink icing around the bottom quarter of the cake. Spread the next-darkest shade of icing above the first layer of icing, then continue with remaining icing. Spread white icing on top of the cake. Garnish with silver dragées. Remove parchment.
Gel colouring goes a long way. Use toothpicks dipped into the gel to get a small amount. Build colours by adding a little bit of gel at a time.
The initial coat of icing is called the crumb coat (because it keeps little bits of cake from marring the finished surface). Chilling the cake after the crumb coat makes it much easier to spread on ombré icing and ensures a beautiful finished cake. (See our how-to video).