Bake the cake: Place the butter and sugar in a bowl and beat with an electric mixer until pale and fluffy.
Add the vanilla and eggs one at a time, mixing with each addition.
In a separate bowl, mix together the flour, baking soda and salt.
Add this to the butter mixture in 2 additions, alternating with sour cream.
Pour some batter into one cavity of a greased and floured small rabbit-shaped cake pan.
(The cake pan is linked in the description box of the YouTube video and if you don't want to purchase one, you can use a mini loaf pan instead.) Add the green sprinkles to the remaining cake batter and mix to combine.
Pour the remaining batter into a greased and floured 9-inch round spring form baking pan, or any deep cake pan.
Bake the cakes at 350F, the rabbit for 15-20 minutes and the round cake for 60-70 minutes, or until a skewer inserted into the middle comes out clean.
Cool for 10 minutes in the pan, then turn out onto a wire rack.
Make the buttercream: Beat the butter with an electric mixer until it is pale and fluffy.
Add the vanilla extract and beat until combined.
Add the confectioner's sugar once cup at a time, then beat for 5 minutes, or until fluffy.
Dye about 2 tablespoons of buttercream pink, 1/3 of the buttercream bright green and leave the remaining buttercream white.
Assembly & Decoration:
First, decorate the rabbit.
Slice any excess cake off the bottom of the rabbit so that it sits flat.
Place some white buttercream in a piping bag fitted with a star-shaped piping tip (#15, 16 or 17).
Pipe dollops over the entire rabbit, adding extra buttercream around the ears, feet and tail.
Place the pink buttercream into a piping bag fitted with a small, round piping tip.
Pipe the rabbit's nose and inside of its ears.
Stick mini chocolate chips onto the rabbit to create its eyes.
Set the rabbit aside.
Flatten the top of the round cake by slicing off the rounded top, then slice it into 3 layers.
Combine 1 cup white buttercream with the strawberries, white chocolate chips and marshmallows.
Spread 1/2 of the buttercream filling between each layer of the cake.
Coat the entire surface of the cake in a thin layer of green buttercream.
Place the rabbit on top of the cake.
Place the green buttercream in a piping bag fitted with a #234 grass piping tip.
Pipe grass over the entire cake.
Scatter some chocolate eggs onto the grass and enjoy!