Preheat oven to 350 degrees. Arrange oven racks in the center of the oven. Grease two 12-cupcake pans with cooking spray or line with cupcake liners.

In a large bowl, sift the flour, baking powder, baking soda, and salt together. Set aside.

In the bowl of an electric stand mixer, using the paddle attachment, beat butter on medium speed with the sugar until it forms a softened paste. Add the eggs in one at a time, beating after each until incorporated. Stop once or twice between adding the eggs to scrape down the sides of the bowl.

Set the mixer to a low speed and alternate between adding the flour mixture and the buttermilk, a little at a time. Once fully incorporated, beat in the vanilla.

Divide the batter evenly between the cupcake pans, filling each cupcake mold three-quarters full. Bake in the oven for 20 to 25 minutes or until a cake tester comes out clean. Transfer the pans to wire racks and cool for at least 15 to 20 minutes, before turning out the cupcakes to cool completely.

While the cupcakes cool, make the blackberry buttercream frosting. Add two sticks of butter to a large bowl and beat with an electric mixer on high for about 1 to 2 minutes. Reduce speed to low and slowly add the confectioner’s sugar, beating until combined. Add the blackberry puree and salt and increase speed to medium. Beat until smooth and fluffy. Set in the refrigerator until you are ready to frost the cupcakes.

Using a cupcake corer (or a small pairing knife), remove the center of each cupcake. The hole you create should be about a 1/2 inch to 3/4 inch deep. Fill each cupcake with approximately 1 to 2 tsp of lemon curd.

Frost cupcakes as desired and garnish with blackberry on top.