Preheat your oven to 350°F (175°C). Grease and flour the two 9-inch round cake pans.
In a mixing bowl, combine the flour, baking powder, and salt. Set aside.
In another large bowl, beat the softened butter and sugar together until light and fluffy using an electric mixer.
Add the eggs one at a time, mixing well after each addition. Then add the vanilla extract.
Gradually add the flour mixture to the butter mixture, alternating with the milk, starting and ending with the flour. Mix until just combined.
Divide the batter evenly between the prepared cake pans. Bake in the preheated oven for 25 minutes or until a toothpick inserted in the center comes out clean.
Remove the cakes from the oven and allow them to cool in the pans for about 10 minutes. Then transfer to a cooling rack to cool completely.
Once cooled, place one layer of cake on a cake stand or platter. Spread a layer of buttercream frosting on top.
Place the second layer of cake on top of the frosted first layer. Use the remaining buttercream frosting to cover the top and sides of the cake.
If desired, sprinkle the shredded coconut over the top and sides of the cake to create a grass effect.
Decorate the cake by placing the Peeps marshmallow chicks on top and around the sides. Add any additional edible decorations as desired.
Slice, serve, and enjoy your festive Peeps Easter Garden Cake!