Preheat your oven to 350°F/175°C and grease two 8 inch cake pans with butter.
In a stand mixer, cream together the butter and white granulated sugar until light in color and fluffy.
Add eggs one at a time, mixing in between each addition until just blended
Add vanilla extract, baking powder and salt and mix again until combined
Slowly add the all-purpose flour while mixing on low speed for about 1 minute or until everything is incorporated
Divide the batter into the two prepared cake pans evenly and bake for 30 minutes or until an inserted toothpick comes out clean
Remove from the oven and let cool completely before decorating with buttercream
To make the buttercream, place softened butter and confectioners' sugar in a stand mixer equipped with whisk attachment. Turn to low speed until all the ingredients are incorporated
Increase the speed of your mixer to high and continue mixing for about 7 minutes or until light in color and fluffy
Add vanilla extract and heavy cream followed by a pinch of salt if desired
Place buttercream into a piping bag and pipe the buttercream all over the cake
Use an offset spatula to even out the buttercream
Wrap foil around the stems of the flowers and insert them into the cake
Enjoy your beautiful flower birthday cake!