1-First Step: Start by preparing the blackberry reduction for your frosting. Take 1 cup of fresh blackberries and place them in a small saucepan over medium heat. Cook them down for about 5-7 minutes, breaking them up with a spoon, until they release their juices and become soft. Use a fine-mesh sieve to strain the seeds out, pressing firmly to extract as much liquid as possible. Let this puree cool completely before using it in the buttercream. This step concentrates the berry flavor and ensures a smooth frosting texture.

2-Second Step: Preheat your oven to 350°F (175°C) and line a standard 12-cup muffin tin with paper liners. In a medium bowl, whisk together the dry ingredients: 1½ cups of all-purpose flour, 1½ teaspoons of baking powder, and ¼ teaspoon of salt. Set this mixture aside. In a large bowl, beat ½ cup of softened unsalted butter and 1 cup of granulated sugar together using an electric mixer on medium speed. Continue beating until the mixture is light and fluffy, which usually takes about 3 minutes. This process incorporates air into the batter, helping the cupcakes rise.

3-Third Step: Add the 2 large eggs one at a time to the butter and sugar mixture, beating well after each addition. Stir in 1 teaspoon of vanilla extract. With the mixer on low speed, gradually add the dry ingredient mixture in three parts, alternating with the ½ cup of buttermilk. Begin and end with the dry ingredients. Mix only until just combined; overmixing can lead to dense, tough cupcakes.

4-Fourth Step: Gently fold in the fresh blackberries. To prevent the berries from sinking to the bottom during baking, toss them in 1 tablespoon of flour before adding them to the batter. Use a spatula to fold them in carefully so you do not crush the fruit.

5-Fifth Step: Divide the batter evenly among the 12 muffin cups, filling each about two-thirds full. An ice cream scoop works perfectly for this task to ensure consistent sizes. Bake for 18-22 minutes. To test for doneness, insert a wooden toothpick into the center of a cupcake. If it comes out clean or with just a few moist crumbs, they are done. Allow the cupcakes to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely. Frosting warm cupcakes will cause the icing to melt, so patience is key here.

6-Final Step: While the cupcakes are cooling, prepare the frosting. In a large bowl, beat ½ cup of softened butter until creamy. Gradually add 4 cups of powdered sugar, one cup at a time, mixing on low speed until incorporated. Add the cooled blackberry puree and 1 teaspoon of vanilla extract. Increase the mixer speed to medium and beat for 2-3 minutes until the frosting is light and fluffy. If the frosting is too thick, add 1-2 tablespoons of milk to reach your desired consistency. Once the cupcakes are completely cool, pipe or spread the buttercream generously on top. Garnish with a fresh blackberry for a pop of color.