Blue Velvet, Blackberry Curd, and Blackberry Lemon Cream Cheese Cupcakes Recipe | Say Mmm

Ingredients

• 1 1/2 cups vegetable oil
• 1 cup buttermilk
• 2 eggs
• 1 teaspoon white vinegar
• 1 teaspoon vanilla extract
• 1 1/2 cups sugar
• 2 1/2 cups all-purpose flour
• 1 teaspoon baking soda
• 1 teaspoon salt
• 1 1/2 tablespoons Dutch-processed cocoa powder
• 2 tablespoons royal blue gel paste food coloring
• 1 tablespoon purple gel paste food coloring
• 2 quarts fresh blackberries
• 1/2 cup water
• 4 tablespoons all-purpose flour
• 1 cup sugar
• 3 eggs
• 2 egg yolks
• 4 tablespoons unsalted butter
• 1 pound cream cheese
• 6 tablespoons unsalted butter
• 2 tablespoons reserved blackberry juice, from curd filling
• 1 lemon, zested
• 5 cups confectioners' sugar