Preheat the Oven: Preheat your oven to 350°F (175°C). Grease and line your cake pans with parchment paper.
Prepare the Cake: In a medium bowl, whisk together the flour, baking powder, and salt. Set aside. In a large mixing bowl, cream the softened butter and sugar together until light and fluffy. Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract and lemon zest.
Combine Wet and Dry Ingredients: Gradually add the dry ingredients to the wet mixture, alternating with the milk. Mix until just combined, being careful not to over-mix.
Bake the Cake: Divide the batter evenly between the prepared cake pans. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Let the cakes cool in the pans for 10 minutes, then transfer to wire racks to cool completely.
Make the Buttercream Frosting: Beat the softened butter in a large bowl until smooth. Gradually add the powdered sugar, one cup at a time, mixing well after each addition. Add the vanilla extract and milk, and beat until fluffy. Divide the buttercream into separate bowls and color each with a few drops of gel food coloring to create pastel shades (pink, lavender, mint, and yellow).
Assemble the Cake: Once the cakes have cooled completely, level the cakes with a cake leveler or knife if necessary. Place the first cake layer on a cake board or stand and frost with a thin layer of buttercream. Add the second layer of cake and cover the entire cake with a smooth layer of buttercream.
Decorate the Cake: Use a piping bag with a petal tip to create flower designs around the cake’s edges. You can pipe rosettes, swirls, or ruffles depending on your preference. Decorate the top of the cake with edible flowers like roses, daisies, or lavender. Add fresh greenery for a natural, garden-inspired look. Optionally, add gold leaf accents for a touch of elegance.
Chill and Serve: Chill the cake in the fridge for 30 minutes to set the decorations. Once ready, slice and serve!