Heat your oven to 340°F and grease three 6-inch round cake pans. While the oven preheats, sift together the flour, baking powder, baking soda, and salt in a small bowl—this aerates the flour and prevents lumps. In a separate bowl, whisk together the sour cream, milk, 3½ teaspoons vanilla, and pink food coloring until well combined. Strain the strawberry preserves through a fine mesh sieve to remove seeds and pulp, which will give you a smoother preserve to work with. Having everything prepared before mixing ensures a smooth, efficient baking process.

In a large mixer bowl, cream together the softened butter and 1 cup sugar until light and fluffy, about 2-3 minutes. Gradually add the dry ingredient mixture from Step 1, alternating with the wet mixture (starting and ending with dry), mixing on low speed just until combined—overmixing creates a dense cake. Divide the batter evenly among the three prepared pans and bake at 340°F for 35 minutes, until a toothpick inserted in the center comes out clean. Remove from oven and let cool in the pans for 10 minutes before turning out onto wire racks to cool completely. I like to let these layers cool to room temperature before frosting, which prevents the frosting from melting.

Combine 4 egg whites, 1½ cups sugar, 1/8 teaspoon salt, and 1/8 teaspoon cream of tartar in a heatproof mixer bowl. Place the bowl over a pot of simmering water (double boiler method) and whisk constantly until the mixture reaches 160°F and feels warm to the touch, about 4-5 minutes—this safely pasteurizes the egg whites. Transfer the bowl to your mixer and beat on medium-high speed for about 15 minutes until the meringue cools completely and reaches stiff, glossy peaks. Gradually add 2¼ cups softened butter in small pieces while the mixer is running, then add 1½ teaspoons vanilla and beat until smooth and creamy. The result should be a silky, stable frosting that's perfect for piping and layering.

Divide the buttercream from Step 3 into portions: reserve about 1 cup for the strawberry version and keep the rest for your gradient colors. For the strawberry frosting, beat together 1¼ cups butter and 1 lb confectioners sugar (sifted) until smooth, then add 1 tablespoon strained strawberry preserve and 2½ tablespoons fresh lemon juice, beating until fully incorporated. For the gradient frosting, take your remaining buttercream and divide it into separate bowls, adding pink and yellow food coloring to create an ombre effect from pale pink to peachy tones. Transfer each frosting variety into piping bags fitted with appropriate tips—I use a grass tip for the strawberry roses and smaller round tips for piping the gradient stripes.

Place the first cooled cake layer on a serving plate or cake board and spread a thin layer of strawberry buttercream from Step 4 on top. Add the second layer and repeat with another layer of strawberry frosting, then top with the final cake layer. Apply a thin crumb coat of strawberry frosting all over the outside of the cake and refrigerate for 10 minutes to set—this prevents crumbs from showing in your final frosting layer. Once chilled, apply a final, thicker layer of strawberry frosting as your base coat, smoothing it as evenly as possible with an offset spatula.

Using the piping bags with colored gradient frosting from Step 4, pipe vertical or horizontal stripes in your chosen pattern across the sides and top of the cake, starting with the palest shade and working toward deeper pink. Smooth the frosting gently with an offset spatula or bench scraper to create an ombré effect, blending the colors slightly where they meet. Chill the cake for 10-15 minutes to set the frosting. While chilled, prepare your decorations: pipe strawberry frosting roses directly onto parchment paper and let them set, then carefully peel away the paper. Top the finished cake with the chocolate bunny, strawberry roses, and chocolate eggs, arranging them artfully on top.