Preheat your oven to 350°F (175°C) and grease three 9-inch round cake pans.
In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.
Add the buttermilk, honey, and vanilla extract to the butter mixture. Mix until well combined.
In a separate bowl, whisk together the all-purpose flour, baking powder, and salt.
Gradually add the dry ingredients to the wet mixture, mixing just until combined. Do not overmix.
Divide the batter evenly among the three prepared cake pans. Smooth the tops with a spatula.
Bake in the preheated oven for 25-30 minutes or until a toothpick inserted into the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes before transferring them to wire racks to cool completely.
While the cakes cool, prepare the frosting by beating the unsalted butter until creamy. Gradually add powdered sugar, mixing on low speed.
Add the heavy cream, vanilla extract, and honey to the frosting mixture. Beat on high speed until fluffy and smooth.
Once the cakes are completely cool, place one layer on a serving plate. Spread a layer of frosting on top.
Add the second cake layer and repeat the frosting process. Place the final layer on top.
Use the remaining frosting to cover the entire cake smoothly, creating a crumb coat.
Roll out the yellow fondant on a clean surface dusted with powdered sugar. Cover the cake with the yellow fondant, smoothing it down the sides.
For the hand-painted characters, roll out the white fondant and cut out shapes for Pooh, Piglet, and other characters.
Use food coloring and fine brushes to paint the characters on the fondant. Allow them to dry before placing them on the cake.
Decorate the cake with the fondant characters, arranging them in a playful scene. Add any additional decorations as desired.
Let the cake set for a few hours before slicing and serving.