Preheat the oven to 350 (F) and center a rack in the oven to the middle position. Prepare three 6-inch cake pans by greasing the sides and lining the bottom of each tin with parchment paper.
In a medium bowl, whisk together 1 3/4 cups cake flour, 1 1/2 teaspoons baking powder and 1/4 teaspoon kosher salt until combined. Set aside.
While the butter and sugar is creaming, combine 4 large egg whites, 1/2 cup whole milk and 1 tablespoon rose water in a liquid measuring cup. Whisk together until well combined.
With the mixer on its lowest speed, add the dry ingredients (from the 2nd step) to the butter and sugar in three parts, alternating with the liquid ingredients (from the 4th step) in 2 parts. Continue mixing until just combined — it's okay to have one or two flour streaks left in the mixture, and at this point, it's better to keep the batter undermixed.
Once the batter is ready, divide evenly into three medium bowls. Add a couple drops of food coloring to each bowl, and use a rubber spatula to stir and incorporate the food coloring into the batter until the batter is one uniform color.
Transfer the different colored batters into its own separate cake pan and transfer to the oven to bake until light golden and just firm, about 18 to 23 minutes. When ready, a skewer inserted into the center of each cake should come out clean. Transfer the pans to a wire rack to cool for 15 minutes, before inverting the layers out of the pans to cool completely before cutting and frosting.
For the Whipped Cream Filling and Topping
When the cakes are completely cooled and ready to be cut, make the whipped cream filling. Combine 1 1/2 cups heavy whipping cream, 1/2 cup confectioner's sugar and 1 teaspoon vanilla extract in a freestanding electric mixer fitted with a whisk attachment. Beat on medium-high speed until soft peaks form, taking care not to overwhisk or you'll end up with butter. Set aside, but make sure you use the cream within 15 minutes of making.
Assembly
Use a 6-inch cake ring or a serrated knife to carefully level and cut the edges and sides off each cake.
Place your base layer onto a cake plate or cake stand, and use a rubber spatula to transfer about 1 cups worth of whipped cream to the top of the cake. Use an offset spatula to carefully distribute the whipped cream around the top of the cake, creating an even layer. Gently nestle the next layer on top of the whipped cream, and repeat until all cake layers are use, topping the final layer with the remaining whipped cream. Serve immediately.