Ingredients
for the cupcakes
1 cup butter, at room temperature
2 cups sugar
3 eggs
2 teaspoons grated lemon peel
2 teaspoons lemon extract
3 1/2 cups all-purpose flour
1 teaspoon baking soda
1/2 teaspoon baking powder
1/2 teaspoon salt
2 cups sour cream
for the filling
1 cup fresh Maine blueberries (reserve a few to garnish if you like)
1/4 cup sugar
1 tablespoon corn starch, mixed with 2 tablespoons cold water
1 teaspoon lemon juice
for the lemon frosting
1 cup (2 sticks) unsalted butter, at room temperature
1/2 cup lemon curd
3 cup confectioners sugar
pinch of salt
for the blueberry frosting
1 cup (2 sticks) unsalted butter, at room temperature
1/2 cup blueberry puree
3 cup confectioners sugar
pinch of salt
for the crumble
1/2 cup butter, softened to room temperature
1/2 light brown sugar
1/2 cup all-purpose flour
1/2 cup oat rolled oats
You will also need a cupcake corer and a dual chamber frosting bag and tip.
Directions
Preheat oven to 350F. Line a standard sized muffin pan with liners.
In the mixing bowl of your stand mixer, cream butter and sugar. Beat in eggs, one at a time. Add lemon peel and vanilla; mix well. Combine dry ingredients; add to creamed mixture alternately with sour cream (batter will be thick). Fill cupcake liners 3/4 full and bake for 25-30 minutes or until a toothpick inserted near the center comes out clean. Cool for 10 minutes; remove to wire racks to cool completely.
Before turning off the oven, make your oatmeal crumble. Combine brown sugar, flour and rolled oats in a medium-sized bowl. Use a pastry cutter or fork to cut the butter into the other ingredients. Line a large baking sheet with silpat or parchment paper. Spread crumble evenly over baking sheet. Bake for 10-13 minutes until it just starts to turn a light brown. Remove and allow to cool. Crumble will harden as it cools. Break apart larger pieces and set aside. You can make this a day ahead of time if you prefer.
While the cupcakes and crumble are cooling, make your filling. In a small saucepan over medium heat, warm blueberries and sugar until the sugar is melted. Once just at boiling, add the corn starch slurry and stir until the mixture comes back up to a boil and thickens. Remove from the heat and add the lemon juice. Cool to room temperature.
To make the frostings, cream together the butter and lemon curd until light and fluffy. Mix in the confectioners sugar a little bit at a time. The frosting may be a little loose, so add a bit more powdered sugar as necessary. Refrigerate to set for 20-30 minutes. For the blueberry, combine butter and blueberry puree until light and fluffy. Mix in the confectioners sugar a little bit at a time. The frosting may be a little loose, so add a bit more powdered sugar as necessary. Refrigerate to set for 20-30 minutes.
To assemble and decorate: Insert a small knife at a 45 degree angle about 1/8 inch from the edge of each cupcake and cut all the way around, remove a cone of cake (or use a cupcake corer, if you have one). Cut away all but the top 1/4 inch of the cone; leaving only a small disk of cake which will be used to top the cupcake. With a small spoon, pour in 2 tablespoons of the blueberry pie filling into the hole (alternatively, you can use a piping bag with no tip). Top with the disk.
Fill frosting types into each chamber of the dual piping bag and decorate as desired. Crumble some of the oatmeal topping and a few blueberries on each cupcake. Keep refrigerated until almost ready to serve.