Preheat oven to 350 degrees. Line the bottom of a giant round cookie pan (or an 8x8, 9x9, 9" pie pan) with parchment paper. Lightly spray the edges of the pan with baking spray, set aside.
In the bowl of a stand mixer, beat together the butter, sugar and extracts until fluffy, about 2-3 minutes. Add one egg, mix then add the egg yolk and mix until combined.
In a medium size mixing bowl, whisk together flour, baking powder, baking soda, salt and cornstarch. With mixing speed on low, gradually add to wet ingredients. Mix until just combined.
Remove bowl from stand and fold in the sprinkles. Pour batter into prepared pan. Smooth out and add a few more sprinkles on top. Place in oven and bake for 20-25 minutes or until the top turns golden brown in color. Remove and place pan on cooling rack. Allow to cool for 30 minutes before removing from pan and frosting.
Meanwhile, to prepare the frosting, in the bowl of a stand mixer, beat together butter, vanilla, heavy cream and salt. With mixing speed on low, gradually add powdered sugar. Turn the speed up to high and beat until fluffy, about 5 minutes. Tint with food coloring if desired.
Pipe frosting around the edges of the cake using a large decorating tip. If desired, using a smaller decorating tip, pipe lettering in the center of the cake. Garnish with additional sprinkles.