Purple Ombre Layer Cake

Ingredients
Vanilla Cake Layers

3½ cups all-purpose flour
2½ tsp baking powder
½ tsp baking soda
1 tsp salt
1¾ cups granulated sugar
1 cup unsalted butter, softened
4 large eggs, room temperature
2 tsp vanilla extract
1¾ cups buttermilk, room temperature
½ cup vegetable oil
Purple gel food coloring (or blueberry puree for natural color) – use gradually for ombre
Vanilla Buttercream Frosting

2 cups unsalted butter, softened
8 cups powdered sugar, sifted
⅓ cup heavy cream
2 Tbsp vanilla extract
Pinch of salt
Step-by-Step Instructions
Preheat oven to 350°F. Grease and line four 8-inch round pans with parchment.
Whisk flour, baking powder, baking soda, and salt in a bowl.
In a large bowl, beat butter and sugar on medium-high until light and fluffy (3–4 minutes).
Add eggs one at a time, beating well after each. Mix in vanilla.
Alternate adding dry ingredients and buttermilk in three additions on low speed, starting and ending with dry.
Mix in oil until just combined—do not overmix.
Checkpoint: Batter should be thick, smooth, and ribbon off the beater slowly.

Divide batter into four portions (about 2 cups each).
Leave one portion as is (lightest layer). Add just a tiny drop of purple coloring to the second portion for a pale lavender.
Add more coloring to the third portion for a medium violet. Add the most to the fourth portion for a deep purple.
Pour into the prepared pans. Gently tap the pans to release air bubbles.
Bake for 22–26 minutes or until a toothpick comes out clean or with a few moist crumbs.
Cool cakes in the pans for 10 minutes, then place on racks to cool completely. If the tops are domed, level the tops.
For the frosting: Beat the butter on medium-high until it is creamy.
Add powdered sugar, 2 cups at a time, while on low, then add cream, vanilla, and salt. Beat on medium-high for 3 minutes until fluffy.
Place the deepest purple layer on a plate. Spread a thin layer of frosting on top.
Stack the medium, pale, and plain layers with frosting in between each layer.
Apply a thin crumb coat over the entire cake and chill for 20 minutes.
Frost the final smooth coat. If desired, decorate with extra frosting swirls or fresh berries.